Principles of zoology : touching the structure, development, distribution and natural arrangement of the races of animals, living and extinct; with numerous illustrations. For the use of schools and colleges. Pt. I. Comparative physiology.

C

EX LH

Come and take choice ofaCCmy Cibrary,
And so beguiCe thy sorrow. " — Shakespeare

JUST PUBLISHED.

PRINCIPLES OF ZOOLOGY,

Touching the Structure, Development, Distribution and Natural
Arrangement of the Races of Animals, living and extinct ; with numer-
ous Illustrations. For the use of Schools and Colleges. Part 1. — Com-
parative Physiology.

BY Louis AQASSIZ AND AUGUSTUS A. GOULD.

EXTRACTS FEOM THE PREFACE.

" The design of this work is to furnish an epitome of the leading princi-
ples of the science of Zoology, as deduced from the present state of
knowledge, so illustrated as to be intelligible to the beginning student. No
similar treatise now exists in this country, and, indeed, some of the topics
have not been touched upon in the language, unless hi a strictly technical
form, and in scattered articles."

" Being designed for American students, the illustrations have been drawn,
as far as possible, from American objects. . . . Popular names have
been employed as far as possible, and to the scientific names, an English
termination has generally been given. The first part is devoted to Com-
parative Physiology, as the basis of Classification ; the second, to System-
atic Zoology, in which the principles of Classification will be applied, and
the principal groups of animals briefly characterized."

NOTICES OF THE PRESS.

" This work has been expected with great interest. It is not simply a
system by which we are taught the classification of Animals, but it is
really what it professes to be, the ' Principles of Zoology,' carrying us on
step by step, from the simplest truths to the comprehension of that infinite
plan which the Author of Nature has established. . . . This book places
us in possession of information half a century in advance of all our element-
ary works on this subject. . . . No work of the same dimensions has
ever appeared in the English language, containing so much new and valu-
able information on the subject of which it treats." — Prof. James Hall, in
the, Albany Journal.

" A work emanating from so high a source as the ' Principles of Zoology,'
hardly requires commendation to give it currency. The public have become
acquainted with the eminent abilities of Prof. Agassiz through his lectures,
and are aware of his vast learning, wide reach of mind, and popular mode
of illustrating scientific subjects. In the preparation of this work, he has
had an able coadjutor in Dr. A. A. Gould, a frequent contributor to the
Transactions of the Boston Society of Natural History, and at present
engaged upon the department of Conchology, for the publication of the late
exploring expedition. The volume is prepared for the student in zoological
science ; it is simple and elementary in its style, full in its illustrations,
comprehensive in its range, yet well condensed, and brought into the narrow
compass requisite for the purpose intended." — Sillimaii's Journal, June, 1848.

" The work is admirably adapted to the use of schools and colleges, and
ought to be made a study in all our higher seminaries, both male and
female." — New York Observer.

" To the testimony which is furnished by their distinguished scholarship,
we may add, however, that the classifications of the work are so admirably
arranged, and its descriptions given with so much simplicity and clearness
of language, that the book cannot fail of its practical aim — to facilitate
the progress of the beginning student. It is a work for schools." —

New York Recorder.

PRINCIPLES OF ZOOLOGY — NOTICES OF THE PKESS.

" The announcement of this work some time ago, as being in a course of
preparation, excited a high degree of interest among teachers, students,
and the friends of science. The names of its authors gave ample assurance
that it was no compilation drawn from other works, no mere reconstruction
of existing materials. The work will undoubtedly meet the expectations
that have been formed of it, and already it has been adopted as a text-book
in several colleges. It breaks new ground ; as is said in the preface, 'some
of its topics have not been touched upon in the language, unless in a strictly
technical form, and in scattered articles.' The volume exhibits throughout
great labor and care in preparing it for the public eye, and for the use of
students. As it has no rival, we suppose its adoption will be almost univer-
sal in literary institutions, and it will do much to awaken in the minds of
multitudes an enthusiastic love of natural history." — Christian Reflector $
Watchman,

" This work is designed as a text book for schools and colleges, and as
an exposition of the interesting science of which it treats, it has many ob-
vious advantages over any other treatise extant. It is the joint production
of two gentlemen, whose researches in natural history have enlarged the
domain'of human knowledge, and one of whom stands confessedly at the
head of the science of the age. It hence contains the latest and most
approved classifications, with explanations and illustrations borrowed from
the forms of animated nature, both living and extinct, and made accurate
and perfect by the fullest acquaintance with the present condition of zoo-
logical science. As a text book it is admirably conceived.

" The presence of Prof Agassiz in the United States, has given a new
impulse to every branch of natural history, and we are happy to find him
thus associated with Dr. Gould, one of our leading American naturalists,
in explaining his favorite science to the youth of our schools and colleges."
Providence Journal.

"No such work had previously appeared in our country. The produc-
tion is worthy of the great names under whose care it has been prepared.
Prof. Agassiz has a world-wide reputation, and Dr. Gould is regarded by the
scientific men of Europe as the most eminent naturalist of our country.
Schools and Academies will find it opens up a new and attractive study
for the young, and in no country is there a finer field opened up to the
naturalist than in our own." — Cliristian Alliance, Boston.

" Anew and highly valuable publication, intended for a school book, but
which will be found equally interesting and important for all to study. . . .
Such a work as this has long been a great desideratum, and we rejoice that
a want so strongly felt, has now, at length, been so well and so completely
supplied." — Boston Atlas.

" This is entirely a new field in American elementary literature, no simi-
lar treatise existing in this country. At fii'st sight, the work appeared to
us too abstruse for beginners, and" for the iise of those whom the author
aims to benefit — the scholars in our common schools. A more careful
examination convinces us that any teacher or scholar, who is in earnest to
understand the subject, will find the application necessary at the commence-
ment comparatively trifling, while the subsequent benefit will be immense.
This is the first volume of the woi'k, and is devoted to Comparative Physi-
ology, on which branch it is exceedingly complete. It is freely illustrated
with the necessary wood cuts. The names of the authors will be a higher
guarantee for scientific accuracy than any judgment we might pronounce."
New York Commercial Advertiser.

" It is designed chiefly for the use of schools and colleges, and as an
epitome of the subject on which it treats, contains more in a small space,
than any book of the kind that has yet fallen under our notice." — Saturday
Gleaner, Philadelphia.

IV. Modern Age.
TTT. Tertiary Age.

II. Secondary Age.

I. Paleozoic Age.
Metamorphic Rocks.

Upper Tertiary Formation.

Lower Tertiary
Cretaceous
Oolitic
Trias

Carboniferous
Devonian
Upper Silurian
Lower Silurian

cc
cc

PRINCIPLES OF ZOOLOGY:

TOUCHING

THE STRUCTURE, DEVELOPMENT, DISTRIBUTION,
AND NATURAL ARRANGEMENT

OF THE

RACES OF ANIMALS, LIVING AND EXTINCT ;

WITH NUMEROUS ILLUSTRATIONS.

FOR THE USE OF SCHOOLS AND COLLEGES.

PART I.

COMPARATIVE PHYSIOLOGY.

BY

LOUIS AGASSIZ,

AND

AUGUSTUS A. GOULD.

BOSTON:
GOULD, KENDALL AND LINCOLN.

59, WASHINGTON STREET.

1848.

Entered according to Act of Congress, in the year 1848,

By GOULD, KENDALL, AND LINCOLN,
in the Clerk's Office of the District Court of the District of Massachusetts.

BOSTON:

PRINTED BY FREEMAN AND BOLLES,
DEVONSHIRE STREET.

PREFACE.

THE design of this work is to furnish an epitome of the
leading principles of the science of Zoology, as deduced
from the present state of knowledge, so illustrated as
to be intelligible to the beginning student. No similar
treatise now exists in this country, and indeed some of
the topics have not been touched upon in the lan-
guage, unless in a strictly technical form, and in scat-
tered articles. On this account, some of the chapters,
like those on Embryology, and Metamorphosis, may
at first seem too abstruse for scholars in our common
schools. This may be the case, until teachers shall have
made themselves somewhat familiar with subjects com-
paratively new to them. But so essential have these
subjects now become to a correct interpretation of phi-
losophical zoology, that the study of them will hereafter
be indispensable. They furnish a key to many phe-
nomena which have been heretofore locked in mystery.

Being designed for American students, the illustra-
tions have been drawn, as far as possible, from American
objects ; some of them are intended merely as ideal
outlines, which convey a more definite idea than if accu-

PREFACE.

rately drawn from nature ; others have been left imper-
fect, except as to the parts especially in question ; a large
proportion of them however, are accurate and original.
Popular names have been employed as far as possible,
and to the scientific names an English termination has
generally been given. Definitions of those least likely
to be understood, may be found in the Index.

The principles of Zoology developed by Professor
Agassiz in his published works have been generally
adopted in this, and the results of many new researches
have been added.

The authors gratefully acknowledge the aid they have
received in preparing the illustrations and working out
the details from Mr. E. Desor, for many years an asso-
ciate of Professor Agassiz, from Count Pourtales and
E. C. Cabot, Esq., and also from Prof. Asa Gray, by
valuable suggestions in the revision of the letter-press.

The first part is devoted to Comparative Physiology
as the basis of Classification ; the second to Systematic
Zoology, in which the principles of Classification will
be applied, and the principal groups of animals will be
briefly characterized.

Should our aim be attained, this work will produce
more enlarged ideas of man's relations to Nature, and
more exalted conceptions of the plan of Creation and
its Great Author.

BOSTON, JUNE 1, 1848.

TABLE OF CONTENTS

Page

INTRODUCTION xiii

CHAPTER FIRST.

THE SPHERE AND FUNDAMENTAL PRINCIPLES OF ZOOLOGY . 1

CHAPTER SECOND.
GENERAL PROPERTIES OF ORGANIZED BODIES ... 11

SECTION I.
Organized and Unorganized Bodies 11

SECTION II.
Elementary Structure of Organized Bodies 13

SECTION III.
Differences between Animals and Plants 17

CHAPTER THIRD.

FUNCTIONS AND ORGANS OF ANIMAL LIFE ... 20

SECTION I.

Of the Nervous System and General Sensation 20

A*

11 TABLE OF CONTENTS.

Page

SECTION II.

Of tJie Special Senses 24

1. Of Sight 24

2. Of Hearing 31

3. Of Smell ... . 36

4. Of Taste .... .... 38

5. Of Touch 39

6. Of the Voice . 40

CHAPTER FOURTH.

OF INTELLIGENCE AND INSTINCT . . 43

CHAPTER FIFTH.

OF MOTION 49

SECTION I.

Apparatus of Motion 49

SECTION H.

Of Locomotion 55

1. Plan of the Organs of Locomotion ... 58

2. Of Standing, and the Modes of Progression . . 64

Walking . 66

Running 67

Leaping • • 67

Climbing 68

Flying 68

Swimming .69

CHAPTER SIXTH.

OF NUTRITION "72

SECTION I.

Of Digestion

Digestive Tube 73

Chymification • 75

Chylification • 76

Mastication 77

Insalivation ... ...

Deglutition

TABLE OF CONTENTS. Ill

Page

CHAPTER SEVENTH.

OF THE BLOOD AND CIRCULATION .... 86

CHAPTER EIGHTH.
OF RESPIRATION ... 92

CHAPTER NINTH.

OF THE SECRETIONS 98

CHAPTER TENTH.
EMBRYOLOGY 102

SECTION I.

Of the Egg 102

Form of the Egg 103

Formation of the Egg 104

Ovulation 105

Laying 105

Composition of the Egg 107

SECTION H.
Development oftJie Young within the Egg 109

SECTION in.
Zoological Importance of Embryology 122

CHAPTER ELEVENTH.

PECULIAR MODES OF REPRODUCTION 125

SECTION I.
Gemmiparous and Fissiparoiis Generation ..... 125

SECTION H.
Alternate and Equivocal Reproduction 127

IV TABLE OF CONTENTS.

SECTION III.
Consequences of Alternate Generation 136

CHAPTER TWELFTH.

METAMORPHOSES OF ANIMALS 142

CHAPTER THIRTEENTH.

GEOGRAPHICAL DISTRIBUTION OF ANIMALS . . . 154

SECTION I.

General Laws of Distribiition .... . 154

SECTION II.

Distribution of the Faunas 161

I. Arctic Fauna 164

n. Temperate Faunas 166

III. Tropical Faunas 172

SECTION III.
Conclusions 175

CHAPTER FOURTEENTH.

GEOLOGICAL SUCCESSION OF ANIMALS ; OR THEIR DISTRIBUTION IN TIME 182

SECTION I.
Structure of tlie Earth's Crust ....'.. 182

SECTION II.

Ages of Nature 189

Paleozoic Age 191

Secondary Age 195

Tertiary Age 201

Modern Age ... 203

Conclusions 205

EXPLANATION OF THE FIGURES.

FRONTISPIECE. — The diagram opposite the title page is intended to present,
at one view, the distribution of the principal types of animals, and the order
of their successive appearance in the layers of the earth's crust. The four
Ages of Nature, mentioned at page 190, are represented by four zones, of
different shades, each of which is subdivided by circles, indicating the num-
ber of formations of which they are composed. The whole disc is divided
by radiating lines into four segments, to include the four great departments
of the Animal Kingdom ; the Vertebrates, with Man at their head, are placed
in the upper compartment, the Articulates at the left, the Mollusks at the right,
and the Radiates below, as being the lowest in rank. Each of these com-
partments is again subdivided to include the different classes belonging to it,
which are named at the outer circle. At the centre is placed a figure to re-
present the primitive egg, with its germinative vesicle and germinative dot
(278), indicative of the universal origin of all animals, and the epoch of life
when all are apparently alike (275, 276). Surrounding this, at the point
from which each department radiates, are placed the symbols of the several
departments, as explained on page 124. The zones are traversed by rays
which represent the principal types of animals, and their origin and termination
indicates the age at which they first appeared or disappeared, all those
which reach the circumference being still in existence. The width of the
ray indicates the greater or less prevalence of the type at different geo-
logical ages. Thus, in the class of Crustaceans, the Trilobites appear to
commence in the earliest strata, and to disappear with the carboniferous
formation. The Ammonites also appeared in the Silurian formation, and did
not become extinct before the deposition of the Cretaceous rocks. The
Belemnites appear in the lower Oolitic beds ; many forms commence in the
Tertiary ; a great number of types make their appearance only in the Modern

VI EXPLANATION OF THE FIGURES.

age ; while only a few have continued from the Silurian, through every
period to the present. Thus, the Crinoids were very numerous in the
Primary Age, and are but slightly developed in the Tertiary and Modern
Age. It is seen, at a glance, that the Animal Kingdom is much more diver-
sified in the later, than in the earlier Ages.

Below the circle is a section, intended to show more distinctly the re-
lative position of the ten principal formations of stratified rocks (461), com-
posing the four great geological ages ; the numerals corresponding to those on
the ray leading to Man, in the circular figure. See also figure 154.

The CHART OF ZOOLOGICAL REGIONS, page 163, is intended to show the
limits of the several Faunas of the American Continent, corresponding to the
climatal regions. And as the higher regions of the mountains correspond in
temperature to the climate of higher latitudes, it will be seen that the northern
temperate fauna extends, along the mountains of Mexico and Central Amer-
ica, much farther towards the Equator, than it does on the lower levels. In
the same manner, the southern warm fauna extends northward, along the
Andes.

FIG.

1. Simple cell, magnified, as seen in the house-leek.

2. Cells when altered by pressure upon each other ; from the pith of elder.

3. Nucleated cells (#), magnified ; b, nucleolated cells.

4. Cartilaginous tissue from a horse, magnified 120 diameters.

5. Osseous tissue from a horse, magnified 450 diameters.

6. Nervous fibres, showing the loops as they terminate in the skin of a frog.

7. Gray substance of the brain, magnified.

8. Head of an embryo fish, to show its cellular structure throughout.

9. Diagram, to show the nervous system of the Vertebrates, as found in

a monkey.

10. Diagram of the nervous system of the Articulates, as seen in a lobster.

11. Diagram of the nervous system of the Mollusks, as found in Natica lieros.

12. Diagram of the nervous system of the Radiates, as found in Scutella

(Echinarachnius par ma) .

13. Section of the eye. a, optic nerve ; b, sclerotic coat ; c, choroid coat ;

d, retina ; e, crystalline lens ; /, cornea ; g, iris ; k, vitreous body ;
ij chamber, divided by the iris.

14. Diagram, showing the effect of the eye on rays of light.

15. Position of the eye of the snail.

16. Eyes (ocelli) of a spider.

17. Eye-spots of a star-fish (Echinaster sanguinolentus) .

18. Compound eyes, showing the arrangement of the facettes, and their con-

nection with the optic nerve, as seen in a crab's eye.

19. Diagram of the human ear, to show the different chambers, canals, and

bones.

EXPLANATION OF THE FIGURES. Vll

FIG.

20. Tympanum and small bones of the ear, twice the natural size ; c, tym-

panum ; m, malleus ; n, incus ; o, orbiculare ; s, stapes.

21. Section of the brain of a crow, showing- the origin of the nerves of the

special senses.

22. Diagram of the larynx, in man.

23. Larynx of the merganser (Mergus merganser} .

24. Nests of Ploceus Philippinus, male and female.

25. Distribution of nerves to the muscular fibres.

26. Test, or crust-like covering of an Echinoderm ( Cidaris) .

27. Muscular ribbons of the willow-moth ( Cossus ligniperda).

28. Vertebra of a cod-fish.

29. Disposition of the muscles of the trout (Salmo tnitta}.

30. Disposition of the muscles of an owl (Strix brachyotis).

31. Jelly-fishes (Stomobrachium crudatum, Hippocrene BougainviUii).

32. Leech, showing the terminal cups.

33. Portion of a Nereis, showing the gills as organs of motion.
34 - 43. Modifications of the fore-arm.

34. Monkey. 35. Deer. 36. Tiger. 37. Whale. 38. Bat.
39. Pigeon. 40. Turtle. 41. Sloth. 42. Mole. 43. Whale.

44. Leg of a beetle.

45. Leg of a lizard.

46. Skeleton of a tiger.

47. Cuttle-fish (Loligo ittecebrosa}.

48. Sea-anemone (Actinia marginata) ', a, mouth ; £, stomach ; c, general

cavity of the body.

49. Planaria, showing the mouth, stomach, and its branches.

50. Jaws, stomach, and intestine of a sea-urchin (Echinus lividus).

51. Plan of the digestive organs of an Insect.

52. Plan of the digestive organs of a land-slug ( TebennopJionis Caroliniensis) .

53. Globules of chyle.

54. Portion of intestine, showing the lacteals of man, and their entrance

into a vein.

55. Jaws of an Echinoderm (Echinarachnius parma).

56. Jaws of a sea-urchin (Echinus granulatus).

57. Beak of a cuttle-fish.

58. Portion of the tongue of a Mollusk (Natica keros), magnified.

59. Jaws of an Annelide (Nereis).

60. Trophi (organs for taking food) of a beetle.

61. " of a bee.

62. 63. " of a squash-bug.

64. " of a butterfly.

65. " of a Rotifer (Brachionus).

66. Jaws of ditto, magnified.

Vlll EXPLANATION OF THE FIGURES.

FIG.

67. Skull of a tiger, showing the muscles for mastication.

68. Head of a snapping-turtle (Emysaimts serpentina) .

69. Head of a "Whale, showing the whalebone.

70. Head of an ant-eater.

71. Head of an alligator.

72. Head of a skate-fish (Myliobatis'), showing the palate bone.

73. Head of a monkey, showing the three different kinds of teeth.

74. Teeth of an insectivorous animal, the mole.

75. Teeth of a carnivorous animal, the tiger.

76. Teeth of a rodent.

77. A polyp ( Tubularia indivisa) ; m> mouth ; 0, ovaries ; p^ tentacles.

78. Blood globules in man, magnified.

79. " in birds, «

80. " " in reptiles, "

81. " " in fishes, "

82. Portion of a vein opened, to show the valves.

83. Network of capillary vessels.

84. Dorsal vessel of an insect, with its valves.

85. Cavities of the heart of mammals and birds.

86. " « " of a reptile.

87. « « " of a fish.

88. Heart and blood vessels of a gasteropod mollusk (Natica).

89. Tracheae, or air tubes of an insect ; s, stigmata ; t} trachea.

90. Relative position of the heart and lungs in man.

91. Respiratory organs of a naked mollusk (Polycera iUuminata).

92. Respiratory organs (gills) of a fish.

93. Vesicles and canals of the salivary glands.

94. Section of the skin, magnified, to show the sweat glands ; a, the leather ;

b, blood-layer ; f, epidermis ; g, gland imbedded in the fat-layer (f),

95. Egg of a skate-fish (Myliobatis') .

96. Egg of hydra.

97. Egg of snow-flea (Podurella).

98. Section of an ovarian egg ; d, germinative dot ; g-, germinative vesicle ;

s, shell-membrane ; v: vitelline membrane.

99. Egg cases of Pyrula. t

100. Monoculus bearing its eggs, a a. <

101. Section of a bird's egg ; #, albumen ; c, chalaza ; e, embryo; s, shell ;

y, yolk.

102. Cell-layer of the germ.

103. Separation of the cell-layer into three layers ; s, serous or nervous layer ;

m, mucous or vegetative layer ; v, vascular or blood-layer.

104. Embryo of a crab, showing its incipient rings.

105. Embryo of a vertebrate, showing the dorsal furrow.

EXPLANATION OF THE FIGURES. IX

FIG.

106-8. Sections of the embryo, showing the formation of the dorsal canal.

109. Section, showing- the position of the embryo of a vertebrate, in relation

to the yolk.

110. Section, showing the same in an articulate (Podurella}.

11^-22. Sections, showing the successive stages of development of the em-
bryo of the white-fish, magnified.

123. Young white-fish just escaped from the egg, with the yolk not yet fully

taken in.

124, 125. Sections of the embryo of a bird, showing the formation of the

allantois ; e, embryo ; x x, membrane rising to form the amnios ;
«, allantois ; ?/, yolk.

126. The same more fully developed. The allantois (a} is further developed,

and bent upwards. The upper part of the yolk (dd) is nearly
separated from the yolk sphere, and is to become the intestine. The
heart (k) is already distinct, and connected by threads with the
blood-layer of the body.

127. Section of the egg of a mammal ; t>, the thick vitelline membrane, or

chorion ; y, yolk ; s, germinative dot ; g, germinative vesicle.

128. The same, showing the empty space (£) between the vitelline sphere

and chorion.

129. Shows the first indications of the germ already divided in two layers,

the serous layer (s}: and the mucous layer (m).

130. The mucous layer (m) expands over nearly half of the yolk, and be-

comes covered with many little fringes.

131. The embryo (e) is seen surrounded by the amnios (£), and covered by

a large allantois (a) ; p e, fringes of the chorion ; pm, fringes of the
matrix.

132. Hydra, showing its reproduction by buds.

133. Vorticella, showing its reproduction by division.

134. Polyps, showing the same.

135. A chain of Salpae.

136. An individual salpa ; m, the mouth ; a, embryos.

137. Cercaria, or early form of the Distoma.

138. Distoma, with its two suckers.

139. Nurse of the Cercaria.

140. The same, magnified, showing the included young.

141. Grand nurses of the Cercaria, enclosing the young nurses.

142. Stages of development of a jelly-fish (Medusa); a, the embryo in Us

first stage, much magnified ; £, summit, showing the mouth ; c, /,
g, tentacles shooting forth ; e, embryo adhering, and forming a pedi-
cle ; h, t, separation into segments ; d, a segment become free ;
£, form of the adult.

143. Portion of a plant-like polyp ( Campanula-rick) ; a, the cup which bears

tentacles ; b, the female cup, containing eggs ; c, the cups in which
the young are nursed, and from which they issue
B

X EXPLANATION OF THE FIGURES.

FlG.

144. Young of the same, with its ciliated margin, magnified.

145. Eye of the perch, containing parasitic worms (Distoma).

146. One of the worms magnified.

147. Transformations of the canker-worm ( Geometra vernalis] ; «, the can-

ker-worm ; ^ its chrysalis ; c, female moth ; d, male moth.

148. Metamorphoses of the duck-barnacle (Anatifa) ; a, eggs, magnified ; £,

the animal as it escapes from the egg ; c, the stem and eye appear-
ing, and the shell enclosing them; d: animal removed from the
shell, and further magnified ; e, /, the mature barnacle, affixed.

149. Metamorphoses of a star-fish (Echinaster sangidnolentus), showing the

changes of the yolk (e) ; the formation of the pedicle (p) ; and the
gradual change into the pentagonal and rayed form.

150. Comatula, a West India species, in its early stage, attached to a stem.

151. The same detached, and swimming free.

152. Longitudinal section of the sturgeon, to show its cartilaginous vertebral

column.

153. Amphioxus, natural size, showing its imperfect organization.

154. Section of the earth's crust, to show the relative positions of the rocks

composing it ; E, plutonic or massive rocks ; M, metamorphic
rocks ; T, trap rocks ; _L, lava. 1. Lower Silurian formation ; 2.
Upper Silurian ; 3. Devonian ; 4. Carboniferous ; 5. Trias, or
Saliferous ; 6. Oolitic ; 7. Cretaceous ; 8. Lower Tertiary or Eo-
cene ; 9. Upper Tertiary, or Miocene, and Pleiocene ; 10. Drift.

155. Fossils of the Paleozoic age ; a, Lingula prima ; b, Leptsena alternata ;

c, Euomphalus hemisphericus ; d, Trocholites ammonius ; e, Avicula
decussata ; f. Bucania expansa ; g, Orthoceras fusiforme ; /', Cya-
thocrinus ornatissimus, Hall ; j, Cariocrinus ornatus, Say ; £, Melo-
crinus amphora, Goldf. ; /, Columnaria alveolata ; m, Cyatho-
phyllum quadrigeminum, Goldf. ; n, o, Caninia flexuosa ; p, Chse-
tetes lycoperdon.

156. Articulata of the Paleozoic age ; o, Harpes ; b, Arges ; c, Brontes ; d,

Platynotus ; e, Eurypterus remipes.

157. Fishes of the Paleozoic age ; a, Pterichthys ; b, Coccosteus ; c , Dipte-

rus ; d, palatal bone of a shark ; e^ spine of a shark.

158. Representations of the tracks of supposed birds and reptiles in the sand-

stone rocks.

159. Supposed outlines of Ichthyosaurus (a), and Plesiosaurus (b).

160. Supposed outline of Pterodactyle.

161. Shells of the Secondary age : a, Terebratula ; b, Goniomya ; c, Trigo-

nia ; c?, Ammonite.

162. Supposed outline of the cuttle-fish («), from which the Belemnite was

derived.

163. Radiata from the Secondary age : a, Lobophyllia flabellum ; b, Litho-

EXPLANATION OF THE FIGURES. XI

FlG.

dendron pseudostylina ; c, Pentacrinus briareus ; cl, Pterocoma

pinnata ; e, Cidaris ; /, Dysaster ; g, Nucleolites.

164. Shells of the Cretaceous formation ; «, Ammonites ; lt Crioceras ; c,

Scaphites ; d, Ancyloceras ; e, Hamites ; f\ Baculites ; g, Turrilites.

165. Shells of the Cretaceous formation : a, Magas ; b, Inoceramus ; c, Hip-

purites ; d, Spondylus ; e, Pleurotomaria.

166. Radiata from the Cretaceous formation : a, Diploctenium cordatum ;

b, Marsupites ; d, Galerites ; c, Salenia ; e, Micraster cor-angninum.

167. Nummulite.

168. Supposed outline of Paleotherium.

169. Supposed outline of Anoplotherium.

170. Skeleton of the Mastodon, in the Cabinet of Dr. J. C. "Warren.

INTRODUCTION,

EVERY art and science has a language of technical terms
peculiar to itself. With those terms every student must
make himself familiarly acquainted at the outset ; and first
of all, he will desire to know the names of the objects about
which he is to be engaged,

The names of objects in Natural History are double, that
is to say, they are composed of two terms. Thus, we speak
of the white-bear, the black-bear, the hen-hawk, the sparrow-
hawk ; or, in strictly scientific terms, we have Felis leo, the
lion, Felis tigris, the tiger, Felis catus, the cat, Canis lupus,
the wolf, Canis vulpes, the fox, Canis familiaris, the dog,
&c. They are always in the Latin form, and consequently
the adjective name is placed last. The first is called the
generic name ; the second is called the trivial, or spe-
cific name.

These two terms are inseparably associated with every ob-
ject of which we treat. It is very important, therefore, to have
a clear idea of what is meant by the terms genus and species ;

XIV INTRODUCTION.

and although the most common of all others, they are not
the easiest to be clearly understood. The Genus is founded
upon some of the minor peculiarities of anatomical struc-
ture, such as the number, disposition, or proportions of the
teeth, claws, fins, &c., and usually includes several kinds.
Thus, the lion, tiger, leopard, cat, &c., agree in the struc-
ture of their feet, claws, and teeth, and they belong to the
genus Felis ; while the dog, fox, jackal, wolf, &c., have
another and a different peculiarity of the feet, claws, and
teeth, and are arranged in the genus Canis.

The Species is founded upon less important distinctions,
such as color, size, proportions, sculpture, &c. Thus we
have different kinds, or species, of duck, different species of
squirrel, different species of monkey, &c., varying from
each other in some trivial circumstance, while those of
each group agree in all their general structure. The spe-
cific name is the lowest term to which we descend, if
we except certain peculiarities, generally induced by some
modification of native habits, such as are seen in domestic
animals. These are called varieties, and seldom endure
beyond the causes which occasion them.

Several genera which have certain traits in common are
combined to form a family. Thus, the alewives, herrings,
shad, &c., form a family called Clupeidse ; the crows,
blackbirds, jays, &c., form the family Corvidae. Families
are combined to form orders, and orders form classes, and
finally, classes are combined to form the four primary divi-
sions of the Animal Kingdom, namely, the departments.

For each of these groups, whether larger or smaller, we
involuntarily picture in our minds an image, made up of the
traits which characterize the group. This ideal image is
called a TYPE, a term which there will be frequent occasion
to employ, in our general remarks on the Animal Kingdom.
This image may correspond to some one member of the

INTRODUCTION. XV

group ; but it is rare that any one species embodies all our
ideas of the class, family, or genus to which it belongs.
Thus, we have a general idea of a bird ; but this idea does
not correspond to any particular bird, or any particular
character of a bird. It is not precisely an ostrich, an owl,
a hen, or a sparrow ; it is not because it has wings, or
feathers, or two legs ; or because it has the power of flight,
or builds nests. Any, or all of these characters would not
fully represent our idea of a bird ; and yet every one has a
distinct ideal notion of a bird, a fish, a quadruped, &c. It
is common however, to speak of the animal which embodies
most fully the characters of a group, as the type of that
group. Thus, we might perhaps regard an eagle as the
type of a bird, the duck as the type of a swimming-bird, and
the mallard as the type of a duck.

As we must necessarily make frequent allusions to ani-
mals, with reference to their systematic arrangement, it
seems requisite to give a sketch of their classification in as
popular terms as may be, before entering fully upon that
subject, and with particular reference to the diagram front-
ing the title-page.

The Animal Kingdom consists of four great divisions
which we call DEPARTMENTS, namely,

I. The department of Vertebrates.

II. The department of Articulates.

III. The department of Mollusks.

IV. The department of Radiates.

I. The department of VERTEBRATES includes all animals
which have an internal skeleton, with a back-bone for its
axis. It is divided into four classes.

1. Mammals (animals which nurse their young).

2. Birds.

3. Reptiles.

4. Fishes.

XVI INTRODUCTION.

The class of MAMMALS is subdivided into three orders.
a. Beasts of prey (Carnivora).
ft. Those which feed on vegetables (Herbivora).
c. Animals of the whale kind (Cetaceans].

The class of BIRDS is divided into four orders, namely,

a. Birds of prey (Incessores}.

b. Climbers (Scansores).

c. Waders (Grallatores).

d. S\vimmers (Natatores).

The class of REPTILES is divided into five orders.

a. Large reptiles with hollow teeth, most of which are

now extinct (Rliizodonts).

b. Lizards (Lacertans).

c. Snakes (Ophidians}.

d. Turtles (Chelonians).

e. Frogs (Batrachians).

The class of FISHES is divided into four orders :

a. Those with enamelled scales, like the gar-pike

(Ganoids], fig. 157.

b. Those with the skin like shagreen, as the sharks

and skates (Placoids).

c. Those which have the edge of the scales toothed,

and usually with some bony rays to the fins, as
the perch (Ctenoids).

d. Those whose scales are entire, and whose fin rays

are soft, like the salmon (Cycloids").

II. Department of ARTICULATES. Animals whose body is
composed of rings or joints. It embraces three classes.

1. Insects.

2. Crustaceans, like the crab, lobster, &c.

3. Worms.

INTRODUCTION. XVII

The class of INSECTS includes three orders.

a. Those which have jaws for dividing their food
(Manducata) fig. 60.

1}. Those with a trunk for sucking fluids, like the but-
terfly, (Suctoria] fig. 62 — 64.

c. Those destitute of wings, like spiders, fleas (Apterd).

The class CRUSTACEANS may be divided as follows :

a. Those furnished with a shield like the crab and

lobster (Malacostracd).

b. Such as are not thus protected (Entomostraca).

c. An extinct race, intermediate between these two

(TriloUtes) fig. 156.

The class of WORMS comprises three orders :

a. Those which have thread-like gills about the head

( Tubulibranchiates).

b. Those whose gills are placed along the sides (Dor-

sibranchiates).

c. Those which have no exterior gills, like the earth-

worm (Abranchiates).

III. The department of MOLLUSKS is divided into three
classes, namely :

1. Those which have arms about the mouth, like the

cuttle-fish (Cepkalopods) fig. 47.

2. Those which creep on a flattened disc or foot, like

snails ( Gasteropods} fig. 88, 89.

3. Those which have no distinct head, and are enclosed

in a bivalve shell, like the clams (Aceplidls).

The CEPHALOPODS may be divided into

a. The cuttle-fishes, properly so called (Teuthideans),

fig. 47.

b. Those having a shell, divided by sinuous partitions

into numerous chambers (Ammonites), fig. 164.

XV111 INTRODUCTION.

c. Those having a chambered shell with simple par-
titions (Nautilus).

The GASTEROPODS contain three orders :

a. The land snails which breathe air (Pidmonates).

b. The aquatic snails which breathe water (Branch'

i/ers), fig. 88.

c. Those which have wing-like appendages about the

head, for swimming (Pteropods).

The class of ACEPHALS contains three orders :

a. Those having shells of two valves (bivalves), like

the clam (Laniellibrancliiates).
I. Those having two unequal valves, and furnished

with peculiar arms (Brachiopods).
c. Mollusks living in chains or clusters, like the Salpa,

or upon plant-like stems, like Flustra (Bryozod),

fig. 135.

IV. The department of RADIATES is divided into three
classes :

1. Sea-urchins, bearing spines upon the surface (Echi-

noderms), figs. 12, 26, 31.

2. Jelly-fishes (Acaleylis), fig. 31.

3. Polyps, fixed like plants, and with a series of flexi-

ble arms around the mouth, figs. 48, 77, 143.

The ECHINODERMS are divided into four orders :

a. Sea-slugs, like biche-le-mar (Holothurians).

b. Sea-urchins (Echini) fig. 26.

c. Free star-fishes (Asteridce), fig. 17.

d. Star-fishes mostly attached by a stem (Crinoids),

fig. 150, 151.

The ACALEPHS include the following orders :

a. The Medusae, or common jelly fishes (Discophori'),
figs. 31, 142.

INTRODUCTION.

b. Those provided with aerial vesicles (Siphonophori).

c. Those furnished with vibrating hairs, by which they

move (Ctenophori).

The class of POLYPS includes three orders.

a. Fresh-water polyps, and similar marine forms (Hy-
dro'ids), fig. 132.

1). Marine polyps, like the sea-anemone and coral-
polyp (Actinoids), figs. 48, 143.

c. A still lower form, allied to the mollusks by their
shell (Rhizopods).

In addition to these, there are numberless kinds of micro-
scopic animalcules, commonly called infusory animals (In-
fusoria), from their being found specially abundant in water
infused with vegetable matter. Indeed, a great many that
were formerly supposed to be animals are now found to be
vegetables. Others are ascertained to be crabs, mollusks,
worms, &c. in their earliest stages of development. In
general, however, they are exceedingly minute, and exhibit
the simplest forms of animal life, and are now grouped
together, under the title of Protozoa. But, as they are still
very imperfectly understood, notwithstanding the beautiful
researches already published on this subject, and as most
of them, are likely to be finally distributed among vegeta-
bles and the legitimate classes in the Animal Kingdom, we
have not assigned any special place for them.

PHYSIOLOGICAL ZOOLOGY

CHAPTER FIRST.

THE SPHERE AND FUNDAMENTAL PRINCIPLES OF

ZOOLOGY.

1. ZOOLOGY is that department of Natural History which
relates to Animals.

2. The enumeration and naming of the animals which
are found on the globe, the description of their forms, and
the investigation of their habits and modes of life are the
principal, but by no means the only objects of this science.
Animals are worthy of our regard not only when considered
as to the variety and elegance of their forms, or their
adaptation to the supply of our wants ; but the Animal
Kingdom, as a whole, has also a still higher signification.
It is the exhibition of the divine thought, as it is carried out
in one department of that grand whole which we call Na-
ture ; and considered as such, it teaches us the most im-
portant lessons.

3. Man, in virtue of his twofold constitution, the spiritual
and the material, is qualified to comprehend Nature.

1

2 SPHERE AND FUNDAMENTAL

Having been made in the spiritual image of God, he is
competent to rise to the conception of His plan and purpose
in the works of Creation. Having also a material body,
like that of animals, he is also prepared to understand the
mechanism of organs, and to appreciate the necessities of
matter, as well as the influence which it exerts over the in-
tellectual element, throughout the whole domain of Nature.

4. The spirit and preparation we bring to the study of
Nature, is not a matter of indifference. When we would
study with profit a work of literature, we first endeavor to
make ourselves acquainted with the genius of the author ;
and in order to know what end he had in view, we must
have regard to his previous labors, and to the circumstances
under which the work was executed. Without this, although
we may perhaps enjoy the perfection of the whole, and ad-
mire the beauty of its details, yet the spirit which pervades
it will escape us, and many passages may even remain un-
intelligible.

5. So, in the study of Nature, we may be astonished at
the infinite variety of her products, and may even study
some portion of her works with enthusiasm, and neverthe-
less remain strangers to the spirit of the whole, ignorant of
the plan on which it is based ; and may fail to acquire a
proper conception of the varied affinities which combine
beings together, so as to make of them that vast picture, in
which each animal, each plant, each group, each class, has
its place, and from which nothing could be removed without
destroying the proper meaning of the whole.

6. Besides the beings which inhabit the earth at the pre-
sent time, this picture also embraces the extinct races which
are now known to us by their fossil remains only. And
these are of the greatest importance, since they furnish us
with the means of ascertaining the changes and modifica-
tions which the Animal Kingdom has undergone in the sue-

PRINCIPLES OF ZOOLOGY.

cessive creations, since the first appearance of living
beings.

7. It is but a short time since it was not difficult for a
man to possess himself of the whole domain of positive
knowledge in Zoology. A century ago, the number of
known animals did not exceed 8000 ; that is to say, from
the whole Animal Kingdom, fewer species were then
known, than are now contained in many private collections
of certain families of insects merely. At the present
day, the number of living species which have been satisfac-
torily made out and described, is more than 50,000.* The
fossils already described exceed 6000 species ; and if we

* The number of vertebrate animals may be estimated at 20,000.
About 1500 species of mammals are pretty precisely known, and the num-
ber may probably be carried to about 2000.

The number of Birds well known is 4 or 5000 species, and the probable
number is 6000.

The Reptiles number about the same as the Mammals, 1500 described
species, and they will probably reach the number of 2000.

The Fishes are more numerous ; there are from 5 to 6000 species in the
museums of Europe, and the number may probably amount to 8 or 10,000.

The number of Mollusks already in collections, probably reaches 8 or
10,000. There are collections of marine shells, bivalve and univalve, which
amount to 5 or 6000 ; and collections of land and fluviatile shells, which
count as many as 2000. The total number of inollusks would therefore
probably exceed 15,000 species.

Among the articulated animals it is difficult to estimate the number of
species. There are collections of coleopterous insects which number 20 to
25,000 species ; and it is quite probable, that by uniting the principal col-
lections of insects, 60 or 80,000 species might now be counted ; for the
whole department of articulata, comprising the Crustacea, the cirrhipeda,
the insects, the red-blooded worms, the intestinal worms, and the infuso-
ria, as far as they belong to this department, the number would already
amount to 100,000 ; and we might safely compute the probable number of
species actually existing, at double that sum.

Add to these about 10,000 for radiata, echini, star-fishes, medusae, and
polypi, and we have about 250,000 species of living animals ; and suppos-
ing the number of fossil species only to equal them, we have, at a very
moderate computation, half a million of species.

4 SPHERE AND FUNDAMENTAL

consider that wherever any one stratum of the earth has
been well explored, the number of species discovered has
not fallen below that of the living species which now inhabit
any particular locality of equal extent, and then bear in
mind that there is a great number of geological strata, we
may anticipate the day when the ascertained fossil species
will far exceed the living species.*

8. These numbers, far from discouraging, should, on the
contrary, encourage those who study Natural History.
Each new species is, in some respects, a radiating point
which throws additional light on all around it ; so that as
the picture is enlarged, it at the same time becomes more
intelligible to those who are competent to seize its promi-
nent traits.

9. To give a detailed account of each and all of these
animals, and to show their relations to each other, is the
task of the Naturalist. The number and extent of the vol-
umes already published upon the various departments of
Natural History show, that only a mere outline of a domain
so vast could be fully sketched in an elementary work, and
that none but those who make it their special study can be
expected to survey its individual parts.

10. Every well-educated person, however, is expected to
have a general acquaintance with the great natural phe-
nomena constantly displayed before his eyes. There is a
general knowledge of man and the subordinate animals,
embracing their structure, races, habits, distribution, mutual
relations, &c., which is calculated not only to conduce es-

* In a separate work, entitled " Nomenclator Zodlogicus^ by L. Agas-
siz, the principles of nomenclature are discussed, and a list of the names of
genera and families proposed by authors is given. To this work those are
referred who may desire to become more familiar with nomenclature, and
to know in detail the genera and families in each class of the Animal
Kingdom.

PRINCIPLES OF ZOOLOGY. O

sentially to our happiness, but which it would be quite inex-
cusable to neglect. This general view of Zoology, it is the
purpose of this work to afford.

11. A sketch of this nature should render prominent the
more general features of animal life, and delineate the ar-
rangement of the species according to their most natural
relations and their rank in the scale of being ; and thus
give a panorama, as it were, of the entire Animal Kingdom.
To accomplish this, we are at once involved in the question,
what is it that gives an animal precedence in rank ?

12. In one sense, all animals are equally perfect. Each
species has its definite sphere of action, whether more or
less extended, — its own peculiar office in the economy of
nature ; and it is perfectly adapted to fulfil all the purposes
of its creation, beyond the possibility of improvement. In
this sense, every animal is perfect. But there is a wide
difference among them, in respect to their organization. In
some it is very simple, and very limited in its operation ; in
others, extremely complicated, and capable of exercising a
great variety of functions.

13. In this physiological point of view, an animal may be
said to be more perfect in proportion as its relations with
the external world are more varied ; in other words, the
more numerous its functions are. Thus, an animal, like a
quadruped, or a bird, which has the five senses fully deve-
loped, and which has, moreover, the faculty of readily
transporting itself from place to place, is more perfect than
a snail, whose senses are very obtuse, and whose motion is
very sluggish.

14. In like manner, each of the organs, when separately
considered, is found to have every degree of complication,
and, consequently, every degree of nicety in the perform-
ance of its function. Thus, the eye-spots of the star-fish
and jelly-fish, probably are endowed with merely the fac-

i*

6 SPHERE AND FUNDAMENTAL

ulty of perceiving light, without the power of distinguishing
objects. The keen eye of the bird, on the contrary, dis-
cerns minute objects at a great distance, and when com-
pared with the eye of a fly, is found to be not only more
complicated, but constructed on an entirely different plan.
It is the same with every other organ.

15. We understand the faculties of animals, and appre-
ciate their value, just in proportion as we become ac-
quainted with the instruments which execute them. The
study of the functions or uses of organs therefore requires
an examination of their structure ; they must never be dis-
joined, and must precede the systematic distribution of ani-
mals into classes, families, genera, and species.

16. In this general view of organization, we must ever
bear in mind the necessity of carefully distinguishing be-
tween affinities and analogies, a fundamental principle re-
cognized even by Aristotle, the founder of scientific Zoology.
Analogy or liomology is the relation between organs or parts
of the body which are constructed on the same plan, how-
ever much they vary in form, but which serve for very dif-
ferent uses. Analogy, on the contrary, indicates the simi-
larity of purposes or functions performed by organs of dif-
ferent structure.

17. Thus, there is an analogy between the wing of a bird
and that of a butterfly, since both of them serve for flight.
But there is no affinity between them, since, as we shall here-
after see, they differ totally in their anatomical relations. On
the other hand, there is an affinity between the bird's wing
and the hand of a monkey, since, although they serve for dif-
ferent purposes, the one for climbing, and the other for flight,
yet they are constructed on the same plan. Accordingly,
the bird is more nearly allied to the monkey than to the
butterfly, though it has the faculty of flight in common with
the latter. Affinities, and not analogies, therefore, must
guide us in the arrangement of animals.

PRINCIPLES OF ZOOLOGY. 7

18. Our investigations should not be limited to adult
animals, but the changes which they undergo during the
whole course of their development must also be considered.
Otherwise, we shall be liable to exaggerate the importance
of certain peculiarities of structure which have a predomi-
nant character in the full-grown animal, but which are
shaded off, and vanish, as we revert to the earlier periods of
life.

19. Thus, for example, by regarding only adult individu-
als, we might be induced to divide all animals into two
groups, according to their mode of respiration ; uniting, on
the one hand, all those which breathe by gills, and, on the
other, those which breathe by lungs. But this distinction
loses its importance, when we consider that various animals,
for example, frogs, which respire by lungs in the adult
state, have only gills when young. It is thence evident that
the respiratory organs cannot be taken as a satisfactory
basis of our fundamental classification. They are, as we
shall see, subordinate to a more important organism, namely,
the nervous system.

20. Again, we have a means of appreciating the relative
grade of animals by the comparative study of their devel-
opment. It is evident that the caterpillar, in becoming a
butterfly, passes from a lower to a higher state. Clearly,
therefore, animals resembling the caterpillar, the worms,
for instance, must occupy a lower rank than those approach-
ing the butterfly, like most insects. There is no animal
which does not undergo a series of changes similar to those
of the caterpillar or the chicken ; only, in many of them,
the most important ones occur before birth, during what is
called the embryonic period.

21. The life of the chicken has not just commenced when
it issues from the egg ; for if we break the egg some days
previous to the time of hatching, we find in it a living ani-

8 SPHERE AND FUNDAMENTAL

mal, which, although imperfect, is nevertheless a chicken ;
it has been developed from a hen's egg, and we know that,
should it continue to live, it would infallibly display all the
characteristics of the parent bird. Now, if there existed in
Nature an adult bird as imperfectly organized as the
chicken on the day, or the day before it was hatched, we
should assign to it an inferior rank.

22. In studying the embryonic states of the mollusks or
worms, we observe in them points of resemblance to many
animals of a lower grade, and to which they at length be-
come entirely dissimilar. For example, the myriads of
minute aquatic animals embraced under the name of Infu-
soria, in their organization generally, very simple, remind
us of the embryonic forms of other animals. We shall have
occasion to show that the Infusoria are not to be considered
as a distinct class of animals, but that among them are
found members of all the lower classes of animals, mollusks,
crustaceans, polyps, and many of them are even found to
belong to the Vegetable Kingdom.

23. Not less striking are the relations that exist between
animals and the regions they inhabit. Every animal has its
home. Animals of the cold regions are not the same as
those of temperate climates ; and these latter, in their turn,
differ from those of tropical regions. Certainly, no one will
maintain it to be the effect of accident that the monkeys,
the most perfect of all brute animals, are found only in hot
countries ; or that it is by chance that the white-bear and
reindeer inhabit only cold regions.

24. Nor is it by chance that the largest of all animals,
of every class, the whales, the aquatic birds, the sea-turtles,
dwell in the water rather than on the land. And while the
water affords freedom of motion to the largest, so is it also
the home of the smallest of living things, affording to them
a freedom from obstacles to their motion, which they could
not enjoy elsewhere.

PRINCIPLES OF ZOOLOGY, 9

25. Nor are our researches to be limited to the animals
now living. There are buried in the crust of the earth the
remains of a great number of animals belonging to species
which do not exist at the present day. Many of these re-
mains present forms so extraordinary that it is almost im-
possible to trace their connection with any animals now
living. In general, they bear a striking analogy to the em-
bryonic forms of existing species. For example, the curi-
ous fossils known under the name of Trilobites (Fig. 156),
have a shape so singular that it might well be doubted to
what group of articulated animals they belong. But if we
compare them with the embryo crab, we find so remarkable
a resemblance that we hesitate not to refer them to the
crustaceans. We shall also see that some of the Fishes of
ancient epochs present shapes entirely peculiar to them-
selves (Fig. 157), but resembling in a striking manner, the
embryonic forms of our common fishes. A determination
of the successive appearance of animals in the order of
time is therefore of much importance in assisting to deter-
mine the relative rank of animals.

26. Besides the distinctions to be derived from the varied
structure of organs, there are others less subject to rigid
analysis, but no less decisive, to be drawn from the imma-
terial principle, with which every animal is endowed. It is
this which determines the constancy of species from gene-
ration to generation, and which is the source of all the va-
ried exhibitions of instinct and intelligence which we see
displayed, from the simple impulse to receive the food which
is brought within their reach, as observed in the polyps,
through the higher manifestations, in the cunning fox, the
sagacious elephant, the faithful dog, and the exalted intel-
lect of man, which is capable of indefinite expansion.

27. Such are some of the general aspects in which we
are to contemplate the animal creation. Two points of

10 FUNDAMENTAL PRINCIPLES OF ZOOLOGY.

view should never be lost sight of, or disconnected, namely,
the animal in respect to its own organism, and the animal
in its relations to creation as a whole. By adopting too ex-
clusively either of these points of view, we are in danger of
falling either into gross materialism, or into vague and
profitless pantheism. He who beholds in Nature nothing
besides organs and their functions, may persuade himself
that the animal is merely a combination of chemical and
mechanical actions and reactions, and thus becomes a mate-
rialist.

28. On the contrary, he who considers only the mani-
festations of intelligence and of creative will, without taking
into account the means by which they are executed, and
the physical laws by virtue of which all beings preserve
their characteristics, will be very likely to confound the
Creator with the creature.

29. It is only as it contemplates, at the same time, matter
and mind, that Natural History arises to its true character
and dignity, and leads to its worthiest end, by indicating to
us, in Creation, the execution of a plan fully matured in the
beginning, and invariably pursued ; the work of a God infi-
nitely wise, regulating Nature according to immutable laws,
which He has himself imposed on her.

CHAPTER SECOND.

GENERAL PROPERTIES OF ORGANIZED BODIES.

SECTION I.

ORGANIZED AND UNORGANIZED BODIES.

30. NATURAL HISTORY, in its broadest sense, embraces
the study of all the bodies which compose the crust of the
earth, or which are dispersed over its surface.

31. These bodies may be divided into two great groups ;
inorganic bodies (minerals and rocks), and living or organ-
ized bodies (vegetables and animals). These two groups
have nothing in common, save the universal properties of
matter, such as weight, color, &c. They differ at the same
time, as to their form, their structure, their composition, and
their mode of existence.

32. The distinctive characteristic of inorganic bodies, is
rest ; the distinctive trait of organized bodies, is independ-
ent motion, LIFE. The rock or the crystal, once formed,
never changes ; their constituent parts or molecules invari-
ably preserve the position which they have once taken in
respect to each other. Organized bodies, on the contrary,
are continually in action. The sap circulates in the tree,
the blood flows through the animal, and in both there is,

12 ELEMENTARY STRUCTURE OF ORGANIZED BODIES.

besides, the incessant movement of growth, decomposition,
and renovation.

33. Their mode of formation is also entirely different.
They are, in the first place, derived from sources unlike
themselves ; and if a mineral is enlarged, it is simply by
the outward addition of particles constituted like itself.
Organized bodies are not formed in this manner. They
always, and necessarily, are derived from beings similar
to themselves ; and once formed, they increase always
from within outward, by the interposition of new particles,
which go to complete the individual.

34. Finally, organized bodies are limited in their dura-
tion. Animals and plants are constantly losing some of
their parts by decomposition during life, which at length
cease to be supplied, and they die, after having lived for a
longer or shorter period. Inorganic bodies, on the con-
trary, contain within themselves no principle of destruction ;
and unless subjected to some foreign influence, a crystal or
a rock would never change. The limestone and granite of
our mountains remain just as they were formed in ancient
geological epochs ; while numberless generations of plants
and animals have lived and perished upon their surface.

SECTION II.

ELEMENTARY STRUCTURE OF ORGANIZED BODIES.

35. The exercise of the functions of life, which is the es-
sential characteristic of organized bodies (32), requires a
degree of flexibility of the organs. This is secured by
means of a certain quantity of watery fluid, which pene-

ELEMENTARY STRUCTURE OF ORGANIZED BODIES. 13

trates all parts of the body, and forms one of its principal
constituents.

36. All living bodies, without exception, are made up of
tissues so constructed as to be permeable to liquids. There
is no part of the body, no organ, however hard and compact
it may appear, which has not this peculiar property. It ex-
ists in the bones of animals, as well as in their flesh and fat ;
in the most solid wood, as well as in the bark and flowers
of plants. It is to this general structure that the term or-
ganism is now applied. Hence the collective name of
organized beings* which includes both the animal and the
vegetable kingdoms.

37. The vegetable tissues and most of the organic struc-

tures, when examined by the microscope,
in their early states of growth, are found
to be composed of hollow vesicles or cells.
The natural form of the cells is that of a
sphere or of an ellipsoid, as may be easily
seen in many plants ; for example, in the

/ V A / tissue of the house-leek (Fig. 1). The

in, ^ — ^v_y '

Fig. i. intervals which sometimes separate them

from each other, are called intercellular passages or spaces
(w). When the cellules are very numerous, and crowd
each other, their outlines become angular, and the intercel-

* Formerly, animals and plants were said to be organized because they
are furnished with definite parts, called organs^ which execute particular
functions. Thus, animals have a stomach, a heart, lungs, &c. ; plants
have leaves, petals, stamens, pistils, roots, &c., all of which are indispen-
sable to the maintenance of life, and the perpetuation of the species. Since
the discovery of the identity of the structure of animal and vegetable tis-
sues, a common denomination for this uniformity of texture, has been
justly preferred ; and the existence of tissues is now regarded as the basis
of organization.

2

14 ELEMENTARY STRUCTURE OF ORGANIZED BODIES.

lular spaces disappear, as seen in figure 2, which represents

the pith of the elder. They then
have the form of a honey-comb ;
whence they have derived their
name of cellules.

38. All the organic tissues, whether
animal or vegetable, originate from
the cell. The cell is to the organ-
ized body what the primary form of the crystal is to the
secondary, in minerals. As a general fact, it may be stated
that animal cells, are smaller than vegetable a b

cells, and contain a central dot or vesicle, called (S© tjfe\
nucleus. Hence those cells are called nucle-
ated cells (Fig. 3, a). Sometimes the nucleus Fig. 3.
itself contains a still smaller dot, called nucleolus (Z>).

39. The elementary structure of vegetables is easily ob-
served in every part of a plant, and its cellular character
has been long known. But with the animal tissues there is
far greater difficulty. Their variations are so great, and
their transformations so diverse, that after the embryonic
period it is often difficult, even by the closest examination,
to detect their original structure.

40. Several kinds of tissues have been designated in the
animal structure ; but their differences are not always well
marked, and they pass into each other by insensible shades.
Their modifications are still a matter of investigation, and
we refer only to the most important distinctions.

41. The areolar tissue. It is the most generally diffused.
The cells are usually large, but irregular, with their walls
often imperfect. In man, as well as in the higher animals,
it is interposed, in layers of various thickness, between the
organs of the body, and contains more or less fat. Most of
the membranes are mere modifications of it.

42. The cartilaginous tissue is composed of nucleated

ELEMENTARY STRUCTURE OF ORGANIZED BODIES. J5

cells, the intercellular spaces being filled with a more com-
pact substance called the hyaline matter. Figure 4 repre-
sents a slip of cartilage from a horse, under
a magnifying power of one hundred and twen-
ty diameters.

43. The osseous or l>ony tissue differs from
the cartilaginous tissue, in having the meshes
filled with salts of lime, instead of hyaline sub-

Fig. 4.

stance, whence its compact and solid appearance. It con-
tains, besides, minute, rounded, or star-like
points, improperly called bone-corpuscles,
which are found to be cavities or canals, and
•^iBO'iis -^r are sometimes fancifully branched, as is seen
^^^^M^^U m figure 5? representing the section of a horse
bone, magnified four hundred and fifty times.

44. The muscular tissue, which forms the flesh of ani-
mals, is composed of bundles of parallel fibres, which, in the
muscles under the control of the will, are commonly crossed
by very fine lines or wrinkles, and possess the peculiar
property of contracting or shortening themselves, under the
influence of the nerves. Every one is sufficiently familiar
with this tissue, in the form of lean meat.

45. The nervous tissue is of different kinds. In the

nerves proper, it is composed of
very delicate fibres, which return
back at their extremities, and form
loops, as shown in figure 7, repre-
senting nervous threads, as they pig. 7.
terminate in the skin of a frog. The same fibrous
structure is found in the white portion of the brain.
But the gray substance is composed of very minute granu-
lations, with larger cells, collected in clusters, as seen in
figure 8.

46. The tissues above enumerated differ from each other

7

16 ELEMENTARY STRUCTURE OF ORGANIZED BODIES.

more widely, in proportion as they are examined in animals
of a higher rank. As we descend in the scale of being,
the differences become gradually effaced. The soft body
of a snail is much more uniform in its composition, than
the body of a bird, or a quadruped. Indeed, multitudes of
animals are known, made up of nothing but cells in contact
with each other. Such is the case with most of the Infu-
soria, which nevertheless live and move most freely, by
means of little hair-like organs at their surface, that are
themselves merely modified cells.

47. A no less remarkable uniformity of structure is to be
observed in the higher animals, in the earlier periods of
their existence, before the body has arrived at its definite
form. The head of the adult salmon, for instance, con-
tains all the tissues we have mentioned, namely, bone,

cartilage, muscle, nerve, brain,
vessels, and membranes. But let
us examine it during the embry-
onic state, that is, while it is yet in
the egg, and we find that the whole
Fig. 3- head is made up of cells which dif-

fer merely in their dimensions ; those at the top of the head
being very small, those surrounding the eye a little larger,
and those beneath being still larger. It is only at a later
period, after still further development, that these cellules
become transformed, some of them into bone, others into
blood, others into flesh, &c.

48. Again, the growth of the body, the introduction of
various tissues, the change of form and structure, proceed in
such a manner as to give rise to several cavities, variously
combined among themselves, and each containing, at the
end of these transformations, peculiar organs, or peculiar
systems of organs.

DIFFERENCES BETWEEN ANIMALS AND PLANTS. 17

SECTION III.

DIFFERENCES BETWEEN ANIMALS AND PLANTS.

49. At first thought, nothing would seem more widely
different than animals and plants. What is there in com-
mon, for instance, between an oak or an elm, and the bird
which seeks shelter under their foliage ?

50. The differences are usually so obvious, that this
question would be superfluous had we to apply it to only the
higher forms of the two kingdoms. But this contrast di-
minishes, in proportion as their construction is simplified ;
and *as we descend to the lower forms, the distinctions
are so few and so feebly characterized, that it becomes
at length difficult to pronounce whether the object we have
before us is an animal or a plant. Thus the sponges have
so great a resemblance to some of the polypi, that they have
generally been classed among animals, although in reality
they belong to the vegetable kingdom.

51. Animals and plants differ in the relative predomi-
nance of the elements, oxygen, carbon, hydrogen and nitro-
gen, of which they are composed. In vegetables, only a
trace of nitrogen is found, and that merely in the seeds, and
some other products of the plant ; while it enters largely
into the composition of the animal tissues.

52. Another peculiarity of the Animal Kingdom is, the
presence of large, distinctly limited cavities, destined for
the lodgment of certain organs ; such is the skull and
the chest in the higher animals, the cavity of the gills in
fishes, and of the abdomen or general cavity of the body,
for the reception of the digestive organs, which exists in all
animals, without exception.

2*

18 DIFFERENCES BETWEEN ANIMALS AND PLANTS.

53. The well-defined and compact forms of the organs
lodged in these cavities, is also another peculiarity of ani-
mals. In plants, the organs designed for special purposes
are not embodied into one mass, but are distributed over
various parts of the individual. Thus, the leaves, which
answer to the lungs, instead of being condensed into one
organ, are scattered in countless numbers over the branches.
Nor is there any one organ corresponding to the brain, the
heart, the liver, or the stomach.

54. Moreover, the presence of a proper digestive cavity,
involves marked differences between the two kingdoms, in
respect to alimentation or the use of food. In plants, the
fluids absorbed by the roots are carried, through the trunk
and all the branches, to the whole plant, before they arrive
at the leaves, where they are to be digested. In animals,
on the contrary, the food is at once received into the digest-
ive cavity, where it is elaborated ; and it is only after it has
been thus dissolved and prepared, that it is introduced into
the other parts of the body.

55. Plants commence their development from a single
point, the seed, and, in like manner, all animals are deve-
loped from the egg. But the animal germ is the result of
successive transformations of the yolk, while nothing similar
takes place in the plant. The subsequent development of
individuals is also different in the two kingdoms. No limit
is placed to the increase of plants ; trees put out new
branches and new roots as long as they live. Animals, on
the contrary, have all a limited size and figure ; and these
once attained, the subsequent changes are accomplished
without any increase of volume or essential alteration of
form ; while the appearance of vegetables is frequently
modified, in a notable manner, by the development of new
branches.

56. In the effects they produce upon the air, by respira-

DIFFERENCES BETWEEN ANIMALS AND PLANTS. 19

tion, there is an important difference. Animals consume
the oxygen, and give out carbonic acid gas which is de-
structive to animal life ; while plants, by respiration, which
they, in most instances, perform by means of the leaves,
reverse the process, and thus furnish oxygen, which is so
essential to animals. If an animal be confined in a small
portion of air, or water containing air, this soon becomes so
vitiated by respiration as to be unfit to sustain life ; but if
living plants are confined with the animal at the same time,
the air is maintained pure, and no difficulty is experienced.
The practical effect of this compensation, in the economy of
Nature, is obviously most important ; vegetation restoring
to the atmosphere what is consumed by animal respiration,
combustion, &c., and vice versa.

57. But there are two things which, more than all others,
distinguish the animal from the plant, namely, the power of
moving itself or its parts at will, and the power of perceiv-
ing other objects or their influences ; in other words, volun-
tary motion and sensation.

58. All animals are susceptible of undergoing pleasure
and pain. Plants have also a certain sensibility. They
wither and fade under a burning sun, or when deprived of
moisture ; and they die when subjected to too great a de-
gree of cold, or to the action of poisons. But they have no
consciousness of these influences, and suffer no pain ; while
animals under similar circumstances suffer. Hence they
have been called animate beings, in opposition to plants,
which are inanimate beings.

CHAPTER THIRD.

FUNCTIONS AND ORGANS OP ANIMAL LIFE.

SECTION I.

OF THE NERVOUS SYSTEM AND GENERAL SENSATION.

59. LIFE, in animals, is manifested by two sorts of func-
tions, viz. : First, the peculiar functions of animal life, or
those of relation, which include the functions of sensation
and voluntary motion ; those which enable us to approach,
and perceive our fellow beings and the objects about us, and
to bring us into relation with them : Second, the functions
of vegetative life, which are nutrition and reproduction ; *
those indeed, which are essential to the maintenance and
perpetuation of life.

60. The two distinguishing characteristics of animals,
namely, motion and sensation (57), depend upon a special
apparatus, which is wanting in plants, and which is called
the nervous system. The nervous system, therefore, is the

* This distinction is the more important, inasmuch as the organs of
animal life, and those of vegetative life, spring from very distinct layers of
the embryonic membrane. The first are developed from the upper layer,
and the second from the lower layer of the germ of the animal. Sec
Chapter on Embryology, p. 112.

NERVOUS SYSTEM AND GENERAL SENSATION.

21

part characteristic of the animal body. It is the grand cen-
tre from which all the commands of the will issue, and to
which all sensations tend.

61. Greatly as the form, the arrangement, and the vol-

ume of the nervous system
vary in different animals,
they may all be reduced to
four principal types, which
correspond moreover, to the
four great departments of the
Animal Kingdom. In the
vertebrate animals, namely,
the fishes, reptiles, birds, and
mammals, the nervous sys-
tem is composed of two prin-
cipal masses, the spinal mar-
row (Fig. 9, c), which runs
along the back, and the
brain, contained within the
skull.* The volume of the
brain is proportionally larger,
as the animal occupies a
more elevated rank in the
scale of being. Man, who
stands at the head of Crea-
tion, is in this respect also, the
9 most highly endowed being.

62. The brain and spinal marrow give origin to the
nerves, which are distributed, in the form of branching
threads, through every part of the body. The branches

* The brain is composed of several distinct parts which vary greatly, in
their relative proportions, in different animals, as will appear hereafter.
They are: 1. The medulla oblongata ; 2. Cerebellum; 3. Optic lobes;
4. Cerebral hemispheres ; 5. Olfactory lobes. See figures 9 and 21.

22 NERVOUS SYSTEM AND GENERAL SENSATION.

which arise from the brain are twelve pairs, called the cere-
bral nerves, and are chiefly destined for the organs of sense
located in the head. Those which arise from the spinal
marrow are also in pairs, one pair for each vertebra or
joint of the back. The number of pairs varies, therefore, in
different classes and families, according to the number of
vertebra?. Each nerve is double, in fact, being composed
of two threads, which spring from the spinal marrow by
separate roots, and accompany each other throughout their
whole course. One of these transmits the commands of the
will, which produce motion ; the other receives and conveys
impressions to the brain, and produces sensations.

63. In the Articulated animals, comprising the crabs,
barnacles, worms, spi-
ders, insects, and oth-
er animals formed of

rings, the nervous sys-
tem consists of a se- Fig. 10.
ries of small centres or swellings, called ganglions (Fig. 10),
placed beneath the alimentary canal, on the floor of the gen-
eral cavity of the body, and connected by threads ; and of a
more considerable mass placed above the oesophagus or
throat, connected with the lower ganglions by threads which
form a collar around the alimentary canal. The number of
ganglions generally corresponds to the number of rings.

64. In the Mollusks (Fig. 11), the nervous system con-

sists of a single ganglionic
circle, the principal swell-
ings of which are placed
symmetrically above and
below the oesophagus, and
from whence the filaments,
Fig. 11. which supply the organs

in different directions, take their origin.

NERVOUS SYSTEM AND GENERAL SENSATION.

23

65. In the Radiata (Fig. 12), the nervous system is re-
duced to a single ring, encircling
the mouth. It differs essentially
from that of the Mollusks, by be-
ing disposed in a horizontal posi-
tion, and by its star-like form.

66. The nerves branch off and
diffuse sensibility to every portion
of the body, and thereby men and
the higher animals are enabled to
Fig. 12. gain a knowledge of the general

properties of the objects which surround them ; every point
of the body being made capable of determining whether
an object is hot or cold, dry or moist, hard or soft. There
are some parts, however, the ends of the fingers, for exam-
ple, in which this sensibility is especially acute, and these
also receive a larger supply of nerves.

67. On the contrary, those parts which are destitute of
sensibility, such as the feathers of birds, the wool of ani-
mals, or the hair of man, are likewise destitute of nerves.
But the conclusive proof that sensibility resides in the
nerves is, that when the nerve which supplies any member
of the body is severed, that member at once becomes insen-
sible.

68. There are animals in which the faculty of percep-
tion is limited to this general sensation ; but their number is
small, and in general, they occupy the lowest place in the
series. Most animals, in addition to the general sensibility,
are endowed with peculiar organs for certain kinds of per-
ceptions, which are called the SENSES. These are five in
number, namely : sight, hearing, smell, taste, and touch.

24 SPECIAL SENSES.

SECTION II.

OF THE SPECIAL SENSES.
1. Of Sight.

69. SIGHT is the sense by which light is perceived, and
by means of which, the form, dimensions, position, color
and brilliancy of surrounding objects, are discerned. Some
of these properties maybe also ascertained, though in a less
perfect manner, by the sense of touch. We may obtain an
idea of the size and shape of an object, by handling it ; but
the properties that have a relation to light, such as color and
brilliancy, and also the form and size of borh^s that are be-
yond our reach, are exclusively recognized by sight.

70. The EYE is the organ of vision. The number, struc-
ture, and position of the eyes in the body, is considerably
varied in the different classes. But whatever may be their
position, these organs are always in connection with particu-
lar nerves, called the optic nerves (Fig. 13, «.). In the ver-
tebrates, these constitute the second pair of the cerebral
nerves, and arise directly from the middle mass of the
brain (Fig. 21, Z>), which, in the embryo, is the most con-
siderable of all.

71. Throughout the whole series of vertebrate animals,
the eyes are only two in num-
ber, and occupy bony cavities

of the skull, called the orbits.
The organ is a globe or hollow
sphere, formed by three mem-
branes enclosed one within the
other, and filled with transpa-
rent matter. Figure 13 repre-
sents a vertical section through Fi
the eye, and will give an idea of the relative position of
these different parts.

OF SIGHT. 25

72. The outer coat is called the sclerotic (Z>) ; it is a thick,
firm, white membrane, having its anterior portion transpa-
rent. This transparent segment, which seems set in the
opaque portion, like a watch-glass in its rim, is called the
cornea (f).

73. The inside of the sclerotic, is lined by a thin, dark
colored membrane, the choroid (c). It becomes detached
from the sclerotic, when it reaches the edge of the cornea,
and forms a curtain behind it. This curtain gives to the eye
its peculiar color, and is called the iris (g). The iris readily
contracts and dilates, so as to enlarge or diminish an
opening at its centre, the pupil, according as more or
less light is desired. Sometimes the pupil is circular, as
in man, the dog, the monkey ; sometimes in the form of a
vertical ellipse, as in the cat ; or, it is elongated sidewise as
in the sheep.

74. The third membrane is the retina (d). It is formed by
the optic nerve, which enters the back part of the eye, by
an opening through both the sclerotic and choroid coats, and
expands upon the interior into a whitish and most delicate
membrane. It is upon the retina that the images of ob-
jects are received, and produce impressions, which are con-
veyed by the nerve to the brain.

75. The fluids which occupy the cavity of the eye, are of
different densities. Behind, and directly opposite to the
pupil, is placed a spheroidal body, called the crystalline
lens (e). It is tolerably firm, perfectly transparent, and com-
posed of layers of unequal density, the interior being
always more compact than the exterior. Its form varies in
different classes of animals. In general, it is more convex
in aquatic than in land animals ; whilst with the cornea, it is
directly the contrary, being flat in the former, and con-
vex in the latter.

76. By means of the iris; the cavity in front of the crys-

3

26 SPECIAL SENSES.

talline is divided into two compartments, called the anterior
and posterior chambers (i). The fluid which fills these
chambers is a clear watery liquid, called the aqueous
humor. The portion of the globe behind the lens, which is
much the largest, is filled by a gelatinous liquid, perfectly
transparent, like that of the chambers, but somewhat more
dense. This is called the vitreous humor (h).

77. The object of this apparatus is to receive the rays of
light, which diverge from all points of bodies placed before
it, and to bring them to a point again upon the retina.
It is a well-known fact, that when a ray of light passes
obliquely from one medium to another of different density,
it will be refracted or turned out of its course more or
less, according to the difference of this density, and the ob-
liquity at which the ray strikes the surface. This may
be illustrated by the following figure. (Fig. 14).

A/ E

Fig. 14.

The ray a c, which strikes the cornea A B perpendicularly,
continues without deviation, until it reaches the bottom of
the eye at c. But the rays am and an, which strike the eye
obliquely, change their direction, and instead of proceeding
onward to mg and nd, take the direction mi and nf. A
still further refraction, though less considerable, is occa-
sioned by passing through the crystalline lens C D, and the
vitreous humor, so that the twro rays m i and nf, will at last
meet in a point. This point is called the focus (c), and in
distinct vision, is always precisely at the retina, E F.

78. From this arrangement, the image found upon the

OF SIGHT. 27

retina, will be inverted. We may satisfy ourselves of this
by direct observation. The eye of the white rabbit being
destitute of the black pigment of the choroid, is quite trans-
parent. Take the eye, soon after the death of the animal,
and arrange it in one end of a tube, so that the cornea will
look outwards ; then if we look through from the other end
of the tube, we may see objects to which it is directed exactly
pictured upon the retina, but in a reversed position.

79. The mechanical structure of the eye, may be per-
fectly imitated by art. Indeed, the camera obscura is an
instrument constructed on the very same plan. By it, exter-
nal objects are pictured upon a screen, placed at the bottom
of the instrument, behind a magnifying lens. The screen
represents the retina ; the dark walls of the instrument
represent the choroid ; and the cornea, the crystalline and
the vitreous humor combined, are represented by the mag-
nifying lens. But there is this important difference, that
the eye has the power of changing its form, and of adapt-
ing it so as to discern with equal precision, very remote,
as well as very near objects.

SO. By means of muscles which are attached to the ball,
the eyes may be rolled in every direction, so as to view ob-
jects on all sides, without moving the head. The eyes are
usually protected by lids, which are two in the mammals,
and generally furnished with a range of hairs at their edges,
called eye-lashes. The birds have a third lid, which is ver-
tical, and is also found in most of the reptiles and a few
mammals. In fishes, the lids are wanting, or immovable.

81. The eye constructed as above described, is called a
simple eye, and belongs more especially to the vertebrate
animals. In man, it arrives at its highest perfection. In
him, the eye also performs a more exalted office than mere
vision. It is a mirror in which the inner man is reflected.
His passions, his joys, and his sorrows, his inmost self, are

28 SPECIAL SENSES.

reflected, with the utmost fidelity, in the expression of his
eye, and it has been rightly called " the window of the
soul."

82. Many of the invertebrate animals, have the eyes
constructed upon the same plan as that of the vertebrate
animals, but with this essential difference, that the optic
nerve which forms the retina, is not derived from a ner-
vous centre, analogous to the brain, but arises from one
of the ganglions. Thus, the eyes of the cuttle-fish contain
all the parts essential to the eye of the superior ani-
mals, and what is no less important, they are only two in
number, placed upon the sides of the head.

83. The snail, and kindred animals
have, in like manner, only two eyes,
mounted on the tip of a long stalk,
(the tentacle), or situated at its base,
or on a short pedestal by its side.
Fig. 15. Their structure is less perfect than

the eyes of the cuttle-fish, but still there is a crystalline,
and more or less distinct traces of the vitreous body.
Some bivalve mollusks, the scollops for example, have
likewise a crystalline, but instead of two, they are fur-
nished with numerous eyes, which are arranged like a bor-
der around the lower margin of the animal.

84. In spiders, the eyes
are likewise simple, and
usually eight in number.
These little organs, usu-
ally called ocelli, instead
of being placed on the
sides of the body or of the
head, occupy the anterior Fig. 16.

part of the back. All the essential parts of a simple eye,
the cornea, the crystalline, the vitreous body, are found in

OF SIGHT. 29

them, and even the choroid, which presents itself in the
form of a black ring around the crystalline. Many insects,
in their caterpillar state, also have simple eyes.

85. Rudiments of eyes have been observed in very
many of the worms. They generally appear as small
black spots on the head ; such as are seen on the head
of the Leech, the Planaria and the Nereis. In these latter
animals there are four spots. According to Mialler, they
are small bodies, rounded behind, and flattened in front,
composed of a black, cup-shaped membrane, containing a
small white, opaque body, which seems to be a continuation
of the optic nerve. It cannot be doubted, therefore, that
these are eyes ; but as they lack the optical apparatus
which produces images, we must suppose that they can only
receive a general impression of light, without the power of
discerning objects.

86. Eye-spots very similar
to those of the Nereis, are
found at the extremity of the
rays of some of the star-fishes,
in the sea-urchins, at the mar- M
gin of many Medusae, and in
some Polypi. M. Ehrenberg
has shown that they also exist
in a large number of the Infu-
soria. Fig 17>

87. In all the animals already mentioned, the eyes, what-
ever their number, are apart from each other. But there is
still another type of simple eyes, known as aggregate eyes.
In some of the millipedes, the pill-bugs, for instance, the
eyes are collected into groups, like those of spiders ; each
eye inclosing a crystalline and a vitreous body, surrounded
by a retina and choroid. Such eyes consequently form a

3*

30

SPECIAL SENSES.

natural transition to the compound eyes of insects, to which
we now give our attention.

88. Compound eyes have the same general form as
simple eyes ; they are placed either on the sides of the head,
as in insects, or supported on pedestals, as in the crabs.
But if we examine an eye of this kind by a magnifying lens,
we find its surface to be composed of an infinite number of
angular, usually six-sided faces. If these fa9ettes are re-
moved, we find beneath, a corresponding number of cones (c),
side by side, five or six times as long as they are broad,
and arranged like rays around the optic nerve, from
which each one receives a little filament, so as to
present, according to Miiller, the following disposition.

(Fig. 18). The cones are per-
fectly transparent, but sepa-
rated from each other by
walls of pigment, in such a
manner, that only those rays
which are parallel to the
axes, can reach the retina A ;
all those which enter ob-
liquely, are lost ; so that of
all the rays which proceed
from the points a and Z>, only the central ones in each
pencil will arrive at the optic nerve (rf) ; the others will
strike against the walls of the cones. To compensate
for the disadvantage of such an arrangement, and for the
want of motion, the number of fafettes is greatly multi-
plied, so that no less than 25,000 have been counted in
a single eye. The image on the retina, in this case, may
be compared to a mosaic, composed of a great number of
small images, each of them representing a portion of the
figure. The entire picture is, of course, more perfect,

18>

OF HEARING. 31

in proportion as the pieces are smaller and more nume-
rous.

89. Compound eyes, being destitute of the optical appara-
tus necessary to collect the rays of light, cannot adapt
themselves to the distance of objects ; they see, but cannot
look. The perfection of their sight depends on the number
of fa^ettes or cones, and the manner in which they are
placed. Their field of vision is wide, when the eye is
prominent ; it is very limited, on the contrary, when the eye
is flat. Thus the dragon-flies, on account of the great
prominency of their eyes, see equally well in all directions,
before, behind, or laterally, whilst the water-bugs, which
have the eyes nearly on a level with the head, can see to
only a very short distance before them.

90. Those animals which are destitute of eyes are
either of a very inferior rank, such as most of the polypi,
or .else they comprise animals which live under unu-
sual circumstances, such as the intestinal worms. Even
among the vertebrates, there are some which lack the fac-
ulty of sight, as the Myxine glutinosa, which has merely a
rudimentary eye concealed under the skin, and destitute of a
crystalline. Others, which live in darkness, have not even
rudimentary eyes, as for example, the fishes which live in
the Mammoth Cave, (Amblyopsis spelceus), and which
appear to want even the orbital cavity. The craw-fishes,
(Astacus pellucidus}) of this same cave, are also blind ;
having merely the pedicle for the eyes, without any
traces of

2. Hearing.

91. To hear, is to perceive sounds. The faculty of per-
ceiving sounds is seated in a peculiar apparatus, the EAR,
which is constructed with a view to collect and augment the
sonorous vibrations of the atmosphere, and convey them to

32

SPECIAL SENSES.

the acoustic or auditory nerve, which arises from the poste-
rior part of the brain. (Fig. 21, c).

92. The ears never exceed two in number, and are
placed, in all the vertebrates, at the hinder part of the head.
In a large proportion of animals, as the dog, horse, rabbit,
and most of the mammals, they are generally quite con-
spicuous externally, and as they are at the same time
quite movable, they become one of the prominent features of
physiognomy.

93. These external appendages, however, do not consti-
tute the organ of hearing, properly speaking. The true
seat of hearing is deeper, quite in the interior of the
head. It is usually a very complicated apparatus, especially
in the superior animals. In mammals it is composed of
three parts, the external ear, the middle ear, and the internal
ear, and its structure is as follows : (Fig. 19).

Fig. 19.

94. The external ear, which is ordinarily regarded as the
ear, consists of the conch, (a), and the canal which leads
from it, the external auditory passage , (b). The first is a

OF HEARING.

33

gristly expansion, in the form of a horn or a funnel, the ob-
ject of which is to collect the waves of sound ; for this rea-
son, animals prick up their ears when they listen ; and for
the same reason, persons who are hard of hearing, em-
ploy an artificial trumpet, by which they may collect the
vibrations from a much more extended surface. The exter-
nal ear is peculiar to mammals ; and is wanting even in a
few aquatic species of these, such as the seals and the
Ornithorynchus. The ear of man is remarkable for being
nearly immovable.

95. The middle ear has received the name of the tym-
panic cavity (k). It is separated from the auditory passage
by a membranous partition, the tympanum or drum (c) ;
though it still communicates with the open air by means
of a narrow canal, called the Eustachian tube, (i) which
opens at the back part of the mouth. In the interior of
the chamber, are four little bones

of singular forms, which anatomists
have distinguished by the names
of malleus (Fig. 20, c), incus (n),
stapes (s), and os orbiculare (o) ;
which are articulated together,
as here represented, so as to form
a continuous chain.

96. The internal ear, which is Fig. 20.

also denominated the labyrinth, is an irregular cavity formed
in the most solid par^ of the temporal bone, beyond the
chamber of the middle ear, from which it is separated by
a bony partition, which is perforated by two small holes,
called, from their form, the round and the oval apertures,
the foramen rotundum, (Fig. 19, g), and the foramen
ovale (h). The first is closed by a membrane, similar to that
of the tympanum, while the latter is closed by the stapes,
one of the little bones in the chamber.

34 SPECIAL SENSES.

97. Three parts are to be distinguished in the labyrinth,
namely, the vestibule, which is the part at the entrance of the
cavity ; the semicircular canals (d), which occupy its upper
part, in the form of three arched tubes ; and the cochlea,
which is a narrow canal placed beneath, at the lower part of
the vestibule, having exactly the form of a snail-shell (e).
The entire labyrinth is filled with a watery fluid, in
which membranous sacs or pouches float. Within these sacs,
the auditory nerve (f) terminates. These pouches, there-
fore, are the actual seat of hearing, and the most essential
parts of the ear. The auditory nerve is admitted to them
by a long passage, the internal auditory canal.

98. By this mechanism, the vibrations of the air are first
collected by the external ear, whence they are conveyed
along the auditory passage, at the bottom of which is the tym-
panum. The tympanum, by its delicate vibrations, augments
the sound, and transmits it to the internal ear, partly by means
of the little bones in the chamber, which are disposed in such
a manner that the stapes exactly fits the oval aperture,
(foramen ovale) ; and partly by means of the air which
strikes the membrane covering the round aperture (g),and
produces vibrations there, analogous to those of the tympa-
num. After all these modifications, the sonorous vibrations
at last arrive at the labyrinth and the auditory nerve,
which transmits the impression to the brain.

99. But the mechanism of hearing is not so complicated
in all classes of animals, and is found to be more and more
simplified, as we descend the series. In birds, the middle
and interior ears are constructed on the same plans as in the
mammals ; but the outer ear no longer exists, and the au-
ditory passage, opening on a level with the surface of the head
behind the eyes, is surrounded only by a circle of peculiarly
formed feathers. The bones of the middle ear are also
jass numerous, there being generally but one.

OF HEARING. 35

100. In reptiles, the whole exterior ear disappears ; the
auditory passage is always wanting, and the tympanum be-
comes external. In some toads, even the middle ear also
is completely wanting. The fluid of the vestibule is
charged with salts of lime, which frequently give it a milky
appearance, and which, when examined by the microscope,
are found to be composed of an infinite number of crystals.

101. In fishes, the middle and external ear are both
wanting ; and the organ of hearing is reduced to a membra-
nous vestibule, situated in the cavity of the skull, and
surmounted by semicircular canals, from one to three in
number. The liquid of the vestibule contains chalky con-
cretions of irregular forms, which are called Otolites, and
whose use is doubtless to render the vibration of sounds
more sensible.

102. In crabs, the organ of hearing is found on the lower
face of the head, at the base of the large antennae. It is a
bony chamber closed by a membrane, in the interior of
which is suspended a membranous sac filled with water.
On this sac, the auditory nerve is expanded. In the cuttle-
fish, the vestibule is a simple excavation of the cartilage of
the head, containing a little membranous sac, in which the
auditory nerve terminates.

103. Finally, some insects, the grasshopper for in-
stance, have a sort of ear, no longer situated in the head,
as with other animals, but in the legs ; and from this fact,
we may be allowed to suppose, that if no organ of hearing
has yet been found in most insects, it is because it
has been sought for in the head only.

104. It appears from these examples, that the part of the
organ of hearing which is uniformly present in all animals
furnished with ears, is precisely that in which the auditory
nerve ends, that is to say, this is the essential part of the or-
gan. The other parts of the apparatus, the tympanum,

36

SPECIAL SENSES.

auditory passage, and even the semicircular canals, have for
their object merely to cause the perception of sound with
more precision and accuracy. Hence we may conclude
that hearing is dull in animals where the organ is reduced
to its most simple form ; and that animals which have
merely a simple membranous sac, without tympanum and
auditory passage, as the fishes, or without semi-circular
canals, as the crabs, perceive sounds but in a very imperfect
manner.

105.

a>

3. Of Smell.

SMELL is the faculty of perceiving odors. Like

sight and hearing,
smell depends upon
special nerves, the
olfactory (a), which
form the first pair
of cerebral nerves,
and which, in the
embryo, are direct

Fig. 21. Head of a Crow. prolongations of the

a, olfactory nerve ; b, optic nerve ; c, auditory i •
nerve ; d, cerebrum ; e, cerebellum.

106. The organ of smell, is the NOSE. Throughout the
series of vertebrates, it makes a part of the face, and in
man, by reason of its prominent form, it becomes one of the
dominant traits of his countenance ; in other mammals, the
nose loses this prominency by degrees, and the nostrils
no longer open downwards, but forwards. In birds, the
position of the nostrils is a little different ; they open farther
back and higher, at the origin of the beak.

107. The nostrils are usually two in number. They are
similar openings, separated by a partition upon the middle
line of the body. In man and the mammals, the outer walls
of the nose are composed of cartilage ; but internally, the

OF SMELL. 37

nostrils communicate with bony cavities situated in the
bones of the face and forehead. These cavities are lined by
a thick membrane, the pituitary membrane, on which are
expanded the nerves of smell, namely, the olfactory nerve,
and some filaments of the nerve which goes to the face.

108. The process of smelling is as follows. Odors are
particles of extreme delicacy which escape from very
many bodies, and are diffused through the air. These par-
ticles are recognized by the nerves of smell only, which
transmit the impressions made by them to the brain.
Smell differs, consequently, from sight and hearing, in being
produced by a material body, and not by a simple undulatory
movement. To facilitate the perception of odors, the
nostrils are placed in the course of the respiratory passages,
so that all the odors which are diffused in the air inspired
pass over the pituitary membrane.

109. The perfection of smell depends on the extent to
which the membrane is developed. Man is not so well
endowed in this respect as many animals, which have the
internal surface of the nostrils extremely complicated, as
it is especially among the beasts of prey.

110. The sense of smell in Reptiles is less delicate than in
the mammals ; the pituitary membrane also is less de-
veloped. Fishes are probably still less favored in this
respect. As they perceive odors through the medium of
water, we should anticipate that the structure of their
apparatus would be different from that of animals which
breathe air. Their nostrils are mere superficial pouches,
lined with a membrane gathered into folds which gen-
erally radiate from a centre, but are sometimes arranged
in parallel ridges on each side of a central band. The
perfection of smell depending on the amount of surface
exposed, it follows that those fishes which have these

4

38 SPECIAL SENSES.

folds most multiplied are also those in which this sense is
most acute.

111. No special apparatus for smell has yet been found
in Invertebrates. And yet there can be no doubt that in-
sects, crabs, and some mollusks perceive odors, since they
are attracted from a long distance by objects which diffuse
them. Some of them may be deceived by odors similar
to those of their prey ; which clearly shows that they are
led by this sense.

4. Of Taste.

112. TASTE is the sense by which the flavor of bodies is
perceived. It guides animals in the choice of their food, and
warns them to abstain from what is noxious. There is
also an intimate connection between the taste and the smell,
so that both these senses are called into requisition in
the selection of food. To perceive the flavor of a body, it
must come into immediate contact with the nerves of taste,
and hence these nerves are distributed at the entrance to
the digestive tube, on the surface of the tongue and the
palate.

113. The nerves of taste are not so strictly special as
those of sight and hearing. They do not proceed from
one single trunk, and, in the embryo, do not correspond to
a particular part of the brain. The tongue in particular,
receives nerves from several trunks ; and taste is perfect in
proportion as the nerves which go to the tongue are more
minutely distributed. The extremities of the nerves gene-
rally terminate in little asperities of the surface, called papil-
la. Sometimes these papillse are very harsh, as in the cat
and the ox ; and again they are very delicate, as in the
human tongue, in that of the dog, horse, &c.

114. Birds have the tongue cartilaginous, sometimes
beset with little stiff points ; sometimes fibrous and fringed

OF TOUCH. 39

at the edges. In the parrots, it is thick and fleshy ;
or it is even barbed at its point as in the woodpeckers.
In some reptiles, the crocodile, for example, the tongue
is adherent ; in others, on the contrary, it is capable of
extensive motion, and serves as an organ of touch, as in the
serpents, or it may be thrust out to take prey, like that of
the chameleon. In fishes it is usually cartilaginous as in
birds, generally adherent, and its surface is frequently cov-
ered with teeth. Some of the inferior animals select their
food with no little discernment. Thus, flies always select
the sugary portions of bodies. Some of the mollusks, as the
snails for example, are particularly dainty in the choice of
their food.

115. It is to be presumed that in animals which have a
cartilaginous tongue the taste must be very obtuse, espe-
cially in those which, like most fishes and many granivorous
birds, swallow their prey without mastication. In fishes,
especially, the taste is very imperfect, as is proved by their
readily swallowing artificial bait. It is probable that they
are guided in the choice of their prey by sight, rather
than by taste or smell.

116. In general, the taste is but imperfectly developed
except in the mammals, and they are the only animals
which enjoy the flavor of their food. With man, the culti-
vation of this sense becomes a matter of study ; and it is
capable of being brought to a high degree of delicacy.

5. Of Touch.

117. The sense of TOUCH is merely a peculiar manifesta-
tion of the general sensibility, seated in the skin, and
dependent upon the nerves of sensation which expand over
the surface of the body. By the aid of this general sensi-
bility, we learn whether a body is hot or cold, wet or dry.
We may also, by simple contact, gain an idea, to a certain

40 SPECIAL SENSES.

extent, of the form and consistence of a body, as for exam-
ple, whether it be sharp or blunt, soft or hard.

118. This faculty resides more especially in the hand,
which is not only endowed with a more delicate tact, but
owing to the disposition of the fingers and the opposition of
the thumb to the other fingers, is capable of so moulding
itself around objects, as to multiply the points of contact.
Hence touch is an attribute of man rather than of other
animals ; for among these latter, scarcely any, except the
monkeys, have the faculty of touch in their hands, or as it
is technically termed, of palpation.

119. In some animals, this faculty is exercised by other
organs. Thus the trunk of the elephant is a most perfect
organ of touch ; and probably the mastodon, whose nume-
rous relics are found scattered in the superficial layers of
the earth's crust, was furnished with a similar organ.
Serpents make use of their tongue for touch ; insects
employ their palpi, and snails their tentacles for the same
purpose.

6. The Voice.

120. Animals have not only the power of perceiving,
but many of them have also the faculty of producing
sounds of every variety, from the roaring of the lion to the
song of the bird as it salutes the rising sun. It is moreover
to be remarked that those which are endowed with a voice,
are precisely those in whom the organ of hearing is most
developed.

121. Animals employ their voice, either for communica-
tion with each other, or to express their sensations, their en-
joyments, their sufferings. Nevertheless, this faculty is en-
joyed by but a small minority of animals ; with but very
few exceptions, only the mammals, the birds, and a few
reptiles are endowed with it. All others are dumb.

OF THE VOICE. 41

Worms and insects have no true voice ; for we must not
mistake for it, the buzzing of the bee, which is merely
a noise created by the vibration of the wings ; nor the
shrill sound of the cricket, which is caused by the friction
of his legs against the wing ; nor the shriek of the locust,
produced by the resonance of his cymbals, when put in vi-
bration by the opening and closing of the wings.

122. Consequently, were the mammals, the birds and the
frogs, to be struck out of existence, the whole Animal King-
dom would be dumb. It is difficult for us, living in the
midst of the thousand various sounds which strike our ear
from all sides, to conceive of such a state. Yet, such a state
did prevail for thousands of ages, on the surface of our globe,
when the watery world alone was inhabited, and before man,
the birds, and the mammals were called into being.

123. In man and the mammals, the voice is formed in an
organ called the larynx, situated at the upper part of the
windpipe, below the bone of the tongue (a).

The human larynx, the part called Adam's NJ //

apple, is composed of several cartilaginous
pieces, called the thyroid cartilage (&), the b-
cricoid cartilage (c), and the small aryte-
noid cartilages. Within these, are found two
large folds of elastic substance, known by the
name of the vocal cords (w). Two other Fig. 22.
analogous folds, the superior ligaments of the glottis (ri),
are situated a little above the preceding. The glottis (o),
is the space between these four folds. The arrangement of
the vocal cords, and of the interior of the glottis in man, is
indicated by dotted lines in Fig. 22.

124. The mechanism of the voice is as follows : the air,
on its way to the lungs, passes the vocal cords. So long as
these are in repose, no sound is produced ; but the moment
they are put upon the stretch, they oppose an obstacle to the
current of air, and it cannot pass without causing them to

4*

42

OF THE VOICE.

vibrate. These vibrations produce the voice ; and as the
vocal cords are susceptible of different degrees of tension,
these tensions determine different sounds ; giving an acute
tone when the tension is great, but a grave and dull one
when the tension is feeble.

125. Some mammals have, in addition, large cavities
which communicate with the glottis, and into which the air
reverberates, as it passes the larynx. This arrangement is
especially remarkable in the howling monkeys, which are dis-
tinguished above all other animals, for their deafening howls.

126. In birds, the proper larynx is very simple, destitute
of vocal cords, and incapable of producing sounds ; but at
the lower end of the windpipe there is a second or inferior
larynx, which is very complicated in structure. It is a kind

of bony drum (a), having with-
in it two glottides, formed at
the top of the two branches (Z>&)
of the windpipe (c), each
provided with two vocal cords.
The different pieces of this ap-
Iparatus are moved by peculiar
muscles, the number of which
varies in different families. In
birds which have a very mono-
|^l tonous cry, such as the gulls,
the herons, the cuckoos, and

the mergansers (Fig. 23), there is but one or two pairs;

parrots have three ; and the birds of song have five.

127. Man alone, of all the animal creation, has the power
of giving, to the tones he utters, a variety of definite sounds ;
in other words, he alone has the gift of speech.

Fig. 23.

CHAPTER FOURTH.

OP INTELLIGENCE AND INSTINCT.

128. BESIDES the material substance of which the body is
constructed, there is also an immaterial principle, which,
though it eludes detection, is none the less real, and to
which we are constantly obliged to recur in considering the
phenomena of life. It originates with the body, and is de-
veloped with it, while yet it is totally apart from it. The
study of this inscrutable principle belongs to one of the
highest branches of Philosophy ; and we shall here merely
allude to some of its phenomena which elucidate the de-
velopment and rank of animals.

129. The constancy of species is a phenomenon depend-
ing on the immaterial nature. Animals, and plants also, pro-
duce their kind, generation after generation. We shall
hereafter show that all animals may be traced back, in the
embryo, to a mere point upon the yolk of the egg, bearing
no resemblance whatever to the future animal. But even
here, an immaterial principle, which no external influence
can prevent or modify, is present, and determines its fu-
ture form ; so that the egg of the hen can produce nothing
but a chicken, and the egg of the cod-fish produces only the
cod. It may therefore be said with truth, that the chicken
and the cod existed in the egg before their formation.

130. PERCEPTION is a faculty springing from this princi-

44 INTELLIGENCE AND INSTINCT.

pie. The organs of sense are the instruments for perceiving
sensations, but they are not the faculty itself, and indeed
without it they would be useless. We all know that the eye
and ear may be open to the sights and sounds about us, but
if the mind happens to be preoccupied, we perceive them
not. We may even be searching for something which actu-
ally lies within the compass of our vision ; the light enters
the eye as usual, and the image is formed on the retina ;
but, to use a common expression, we look without seeing,
unless the mind that perceives is directed to the object.

131. In addition to the faculty of perceiving sensations,
the higher animals have also the faculty of recalling
past impressions, or the power of memory. Many animals
retain a recollection of pleasure or pain that they have
experienced, and seek or avoid the objects which these sen-
sations may have produced ; and in doing so, they give
proof of judgment.

132. Finally, we notice in some animals acts which
prove that they have the faculty of comparing their sensations
and their judgments ; in other words, that they carry on a
process of reasoning.

133. These different faculties, taken together, constitute
intelligence. In man, this superior principle, which is an
emanation of the divine nature, manifests itself in all its
splendor. God " breathed into him the breath of life, and
man became a living soul." It is his prerogative, and his
alone, to be enabled to guide his conduct by the deductions
of reason ; he has not only the faculty of exercising his
judgment upon the objects which surround him, and of ap-
prehending the many relations which exist between himself
and the external world ; he may also apply his reason to
immaterial things, observe the operations of his own intel-
lect, and, by the analysis of his faculties, may arrive at the
consciousness of his own nature, and even conceive of
that Infinite Spirit, " whom none by searching can find out."

INTELLIGENCE AND INSTINCT. 45

134. Other animals cannot aspire to conceptions of this
kind ; they contemplate merely those objects which imme-
diately strike the senses, and without exercising any con-
tinuous effort of the reasoning faculty in regard to them.
Their conduct, moreover, is regulated by another princi-
ciple of inferior order, still derived from the immaterial
principle, called INSTINCT.

135. Under the guidance of Instinct, animals are enabled
to perform certain operations, without instruction, in one un-
deviating manner. When man chooses wood and stone, as
the materials for his dwelling, in preference to straw and
leaves, it is because he has learned by experience, or because
his associates have informed him, that these materials are
more suitable for the purpose. But the bee requires no in-
structions in building her comb. She selects, without hesita-
tion, the fittest materials ; and the young bee exhibits, in this
respect, as much discernment as those who have had the
benefit of long experience. She performs her task without
previous study, and, according to all appearances, without
the consciousness of its utility, being in some sense impelled
to it by a blind impulse.

136. If, however, we judge of the instinctive acts of ani-
mals compared with the acts of intelligence, by the relative
perfection of their products, we may be led into gross errors,
as a single example will show. No one will deny that the
honey-comb is constructed with more art and care than the
huts of many tribes of men. And yet, who would presume
to conclude from this, that the bee is superior in intelligence
to the inhabitant of the desert or of the primitive forest ?
It is evident, on the contrary, that in this particular case, we
are not to judge of the artisan by his work. As a work of
man, a structure as perfect in all respects as the honey-
comb would indicate very complicated mental operations,
and probably numerous preliminary experiments.

46 INTELLIGENCE AND INSTINCT;

137. The instinctive actions of animals relate either to
the procuring of food, or to the rearing of their young ;
in other words, they have for their end the preservation of
the individual and of the species. It is by instinct that the
leopard conceals himself, and awaits the approach of his
prey. It is equally by instinct that the spider spreads his
web to entangle the flies which approach it.

138. Some animals go beyond these immediate precau-
tions ; their instinct leads them to make provision for the
future. Thus the squirrel lays in his store of nuts and
acorns during autumn, and deposits them in cavities of
trees, which he readily finds again in winter. The hamster
digs, by the side of his burrow, compartments for magazines,
which he arranges with much art. Finally, the bee,
more than any other animal, labors in view of the future ;
and for this reason, she has become the emblem of order
and domestic economy.

139. Instinct exhibits itself, in a no less striking manner,
in the anxiety which animals manifest for the welfare of
their anticipated progeny. All birds build nests for the
shelter and nurture of their young, and in some cases, these
nests are made exceedingly comfortable. Others show
very great ingenuity in concealing their nests from the eyes
of their enemies, or in placing them beyond their reach.
There is a small bird in the East Indies, the tailor bird,
(Sylvia sutoria), which spins wool or cotton into threads,
with its feet and beak, and uses it to sow together the
leaves of trees for its nest.

140. The nest of the fiery hang-bird, (Icterus Baltimore),
dangling from the extremity of some slender, inaccessible
twig, is familiar to all. The beautiful nest of the humming-
bird, seated on a mossy bough, and itself coated with lichen
and lined with the softest down from the cotton-grass or the
mullein leaf, is calculated equally for comfort and for es-
caping observation. An East Indian bird, (Ploceus Philippi-

INTELLIGENCE AND INSTINCT. 47

nus,) not only exhibits wonderful devices in the construction,
security, and comfort of its nest, but displays a still further
advance towards intelligence. The nest is built at the tips
of long pendulous twigs, usually hanging over the water. It
is composed of grass, in such a manner as to form a com-
plete thatch. The entrance
is through a long tube run-
ning downwards from the
edge of the nest ; and the
lower end of it is so imper-
fectly woven, that any ser-
pent or squirrel, in attempting
to enter the aperture, would
detach the fibres, and fall to
the ground. But the male,
who has no occasion for a
nest, builds his thatched dome,
similar to that of the female, Fig. 24.

and by its side ; but makes simply a perch across the bottom
of the dome, without the nest-pouch or tube.

141. But it is among insects, that this instinctive solici-
tude for the welfare of the progeny is everywhere exhibited
in the most striking manner. The bees and wasps not only
prepare cells for each of their eggs, but take care, before
closing the cells, to deposite in each of them something ap-
propriate for the nourishment of the future young.

142. It is by the dictate of instinct also, that vast numbers
of animals of the same species associate, at certain periods
of the year, for migration from one region to another ; as
the swallows and passenger pigeons, which are sometimes
met with in countless flocks.

143. Other animals live naturally in large societies, and
labor in common. This is the case with the ants and bees.
Among the latter, even the kind of labor for each member
of the community is determined beforehand, by instinct.

48 INTELLIGENCE ANL> INSTINCT.

Some of them collect only honey and wax ; while others
are charged with the care and education of the young ; and
still others, are the natural chiefs of the colony.

144. Finally, there are certain animals so guided by their
instinct as to live like pirates, on the avails of others'
labor. The Lestris or Jager will not take the trouble to
catch fish for itself, but pursues the gulls, until, worn out
by the pursuit, they eject their prey from their crop. Some
ants make war upon others less powerful, take their young
away to their nests, and oblige them to labor in slavery.

145. There is a striking relation between the volume of
the brain, and the degree of intelligence which an animal
may attain. The brain of man is the most voluminous
of all, and among other animals there is every grada-
tion in this respect. In general, an animal is the more
intelligent, in proportion as its brain bears a greater re-
semblance to that of man.

146. The connection between instinct and the nervous
system does not present so intimate a correspondence as
exists between the intellect and the brain. Animals which
have a most striking development of instinct, as the ants and
bees, belong to a division of the Animal Kingdom where the
nervous system is much less developed than that of the ver-
tebrates, since they have only ganglions, without a proper
brain. There is even a certain antagonism between instinct
and intelligence, so that instinct loses its force and peculiar
character, whenever intelligence becomes developed.

147. In man, instinct plays but a secondary part, but he
is not entirely devoid of it. Some of his actions are entirely
prompted by instinct, as for instance, the attempts of the in-
fant to nurse. This fact again, that instinctive actions pre-
ponderate in infancy, when intelligence is but slightly de-
veloped, goes to confirm the two last propositions.

CHAPTER FIFTH.

OF MOTION.
SECTION I.

APPARATUS OF MOTION.

148. THE power of voluntary motion is the second grand
characteristic of animals (57). Though they may not all
have the means of transporting themselves from place to
place, there is no one which has not the power of executing
some motions. The oyster, although fixed to the ground,
opens and closes its shell at pleasure ; and the little coral
animal protrudes itself from its retreat, and retires again at
its will.

149. The movements of animals are effected by means
of muscles, which are organs designed expressly for this
purpose, and which make up a large portion of the body,
that part which is commonly called flesli. They are com-
posed of a series of fleshy bundles, which are readily seen
in boiled meat. These bundles are again composed of par-
cels of still more delicate fibres, called muscular fibres (45),
and in which alone the property of elongation and contrac-
tion resides.

150. The motions of animals and plants depend, there-
fore, upon causes essentially different. The expansion and

5

50

APPARATUS OF MOTION.

closing of the leaves and blossoms of plants, which are their
most obvious motions, are due to the influence of light, heat,
moisture, cold, and similar external agents ; but all the mo-
tions peculiar to animals are produced by a cause residing
within themselves, namely, the contractility of muscular

fibres.

151. The cause which determines contractility resides in
the nerves, although its action is not precisely known.

We only know that
each muscular bun-
dle receives one or
more nerves, whose
filaments pass across

in the figure. It has
also been shown, by

Fig. 25. experiment, that when

a nerve going from the brain to a muscle is severed, the
muscle instantly loses its power of contracting, or, in other
words, is paralyzed.

152. The muscles may be classified, according as they
are more or less under the control of the will. The con-
tractions of some of them are entirely dependent on the
will, as the muscles of the limbs which are used for locomo-
tion. Others are quite independent of it, like the con-
tractions of the heart and stomach. The muscles of res-
piration act independently of the will, but are partially sub-
ject to it ; thus, when we attempt to hold the breath, we
arrest, for the moment, the action of the diaphragm.

153. In the great majority of animals, motion is greatly
aided by the presence of solid parts, of a bony or horny
structure, which either serve as firm attachments to the
muscles, or, being arranged so as to act as levers, they

APPARATUS OF MOTION. 51

increase the force and precision of the movements. The
solid parts are usually so arranged as to form for the body
a substantial frame work, which has been variously desig-
nated in the several classes of animals, as the test, shell,
carapace, skeleton, fyc. The study of these solid parts con-
stitutes the most important branch of comparative anatomy.
Their characters are the most constant and enduring of all
others. Indeed, these solid parts are all that remains to us of
the numerous extinct races of animals of past geological
eras ; and from these alone, we are to determine the struc-
ture and character of the ancient fauna.

154. Most of the Radiata have a calcareous test or crusty
shell. In the Polypi, this structure, when it exists, is usually
very solid, sometimes in the form of a simple internal
stem, or extensively branched, as in the sea-fans ; and
sometimes in solid masses, furnished at the sides with nu-
merous cavities, in which the animals are lodged, with the
power, however, of protruding and retracting themselves at
pleasure, by means of their muscles, as in the corals. In
the Echinoderms, the test is brittle, and intimately united
with the soft parts. It is composed

of numerous little plates, some-
times consolidated and immovable,
as in the sea-urchins, (Fig. 26),
and sometimes so combined, as to
allow of various motions, as in the Fig. 26.

star- fishes, (Fig. 17), which use their arms both for crawl-
ing and swimming.

155. In the Mollusks, the solid parts are secreted by the
skin, most frequently in the form of a calcareous shell of
one, two, or many pieces, serving for the protection of the
soft parts which they cover. These shells are generally so
constructed as to allow the animal to retire and conceal
itself completely within their cavities. In a few, the shell

52 APPARATUS OF MOTION.

is too small for this purpose, and in some it exists only at
a very early period, and is lost as the animal is de-
veloped, so that at last there is no other covering than a
slimy skin. In others, the skin becomes so thick and firm
as to have the consistence of elastic leather ; or it is gelati-
nous or transparent, and what is very curious, the tissues
are the same as those of woody fibre, as for example, in the
Ascidia. As a general thing, these solid parts do not aid in
locomotion, so that the mollusksare mostly sluggish animals.
It is only in a few rare cases that the shell becomes a true
lever, as in the Scollops, (Pecten) which use their shells as
oars, in swimming.

156. The muscles of mollusks either form a flat disc,
or are distributed in the skin so as to dilate and contract it,
or are arranged about the mouth and tentacles, which they
put in motion. However varied the disposition of the muscles
may be, they always form very considerable masses, in pro-
portion to the size of the animal, and have a soft and mu-
cous appearance, such as is not seen in the contractile fibres
of the other departments of the Animal Kingdom. This pe-
culiar aspect no doubt arises from the numerous small
cavities found in the muscles, and the mucous glands which
are distributed through them.

157. In the Articulated animals, the solid parts are rings,
generally of a horny structure, but sometimes calcareous,
and successively fitting into each other. The tail of a
lobster gives a good idea of this structure, which differs, in
the several classes of this department, merely as to volume,
form, solidity, number of pieces, and the degree of motion
which one ring has upon another. In some groups the
rings are consolidated, so as to form a shield or carapace,
such as we see in the crabs. In others, the rings are so
soft that the body is capable of changing into every possi-
ble form, as in the leeches and worms generally.

APPARATUS OF MOTION.

53

158. A variety of appendages are attached to these
rings, such as jointed legs, or in place of them, stiff bristles,
oars fringed with silken threads, wings either firm or mem-
branous, tentacles or antenna?, movable arms which per-
form the office of jaws, &c. But, however diversified this
solid apparatus may be, it is universally the case that the
rings, to which every part may be referred as to a type,
constitute but a single simple cavity, in which all the organs
are enclosed, the nervous system as well as the organs
of vegetative life (63).

159. The muscles which move
all these parts have this peculiar-
ity, that they are all situated within
the solid parts, and not on their ex-
ternal face, as in the vertebrates ;
and also that the muscular bundles,
which are very considerable in
number, have the form of ribbons,
or fleshy strips, with parallel
fibres of remarkable whiteness.

Figure 27 represents the disposi- Fig. 27.

tion of the muscles of the caterpillar which destroys the
willow, (Cossus ligniperdd). The right side represents
the superficial layer of muscles, and the left side the deep-
seated layer.

160. The Vertebrata, like the articulated animals, have
solid parts at the surface, as the hairs and spines of mam-
mals, the feathers and claws of birds, the bucklers and
scales of reptiles and fishes, &c. But they have besides
this, throughout the interior of the whole body, a solid
framework not found in the other departments, well known
as the SKELETON.

161. The skeleton is composed of a series of separate

5*

54

APPARATUS OF MOTION.

bones, called vertebrse, united to each other by ligaments.
Each vertebra has a solid centre with four branches, two of
A, which ascend and form an arch above, and

two descend, forming an arch below the
body of the vertebra. The upper arches
form a cavity (a) which, along the region
of the trunk, encloses the spinal marrow,
and in the head receives the brain (61).
The lower arches (Z>) form a cavity, simi-
lar to the superior one, for containing the
organs of nutrition, and reproduction ;
they sometimes meet below, but generally
they remain separated, so that the inferior
cavity of the body is enclosed, in part, by
fleshy walls. Every part of the skeleton
may be reduced to this fundamental type,
the vertebra, as will be shown, when treating especially of
the vertebrate animals ; so that between the pieces of
the head, the trunk, or the tail, we have only differences
in the degree of development of the body of the ver-
tebra, or of its branches, and not different plans of organ-
ization.

162. The muscles which move this solid frame -work of
the vertebrata are disposed around the vertebrae, as is

Fig. 28.

Fig. 29.

well exemplified among the fishes, where there is a band
of muscles for each vertebra. In proportion as limbs

LOCOMOTION.

55

are developed, this intimate relation between the mus-
cles and the vertebra
goes on diminishing. The
muscles are more con-
centrated about the limbs,
where the greatest amount
of muscular force is re-
quired. For this reason,
the largest masses of flesh,
in the highest vertebrates
are found about the shoul-
ders and hips ; while in
the fishes, they are con-
centrated about the tail, Fig. so.
which is the part on which they principally depend for
motion.

SECTION II.

OF LOCOMOTION.

163. One of the most curious and important applications
of this apparatus of bones and muscles, is that for LOCOMO-
TION. By this is understood the movement by which an
animal passes from place to place, in the pursuit of pleasure,
sustenance or safety, in distinction from those motions
which are performed equally well while stationary, such
as the acts of respiration, mastication, &c.

164. The means which nature has brought into action to
effect locomotion under all the various circumstances in
which animals are placed, are very diversified ; and the
study of their adaptation to the necessities of animals is one
of the highest interest in a mechanical, as well as in a
zoological point of view. Two general plans may be noticed,

56 LOCOMOTION.

under which these varieties may be arranged. Either the
whole body is concerned in effecting locomotion, or only
some of its parts are employed for the purpose.

165. The jelly-fishes (Medusaa)
swim by contracting their umbrella-
shaped bodies upon the water con-
tained within, and its resistance
urges them forwards. Many others
are provided with a sac or siphon,
which they fill with water. By fore-
Fig. 31. ing out the water suddenly, a jet is
produced, which is resisted by the surrounding water, and
the animal is thus propelled. The Biche-le-mar, (Holo-
thuria), the cuttle-fishes, the Salpas, &c., employ this method.

166. Others contract small portions of the body in suc-
cession, which being thereby rendered firmer, serve as
points of resistance, against which the animal may strive,
in urging the body onwards. The earth-worm, whose body
is composed of a series of rings united by muscles, and
shutting more or less into each other, has only to close up
the rings at one or more points, to form a sort of fulcrum,
against which the rest of the body exerts itself in extend-
ing forwards.

O

167. Some have, at the extremities of the body, a cup or
some other organ for maintaining a firm hold, each one
acting in turn as a fixed point. Thus the Leech has a cup
or sucker at its tail, by which it fixes itself ; the body is
then elongated by the contrac-
tion of the muscular fibres!

which encircle the animal ; the

other end is fixed by a similar |

sucker, then by the contraction Fig. 32.

of muscles running lengthwise, the body is shortened, and

the tail is brought forwards to perform the same process

LOCOMOTION. 57

again. Most of the bivalve mollusks, such as the clams,
move from place to place, in a similar way. A fleshy
organ, called the foot, is thrust forward, and its extremity
fixed in the mud or to some firm object, when it contracts,
and thus draws along the body, and the shell enclosing it.
The snails and many similar animals have the under surface
of the body composed of an infinitude of very short muscles
which, by successive contractions, so minute indeed as
scarcely to be detected, enable them to glide along smoothly
and silently, without any apparent muscular effort.

168. In the majority of animals, however, locomotion is
effected by means of organs specially designed for the pur-
pose. The most simple organs are the minute hair-like
cilicR, which cover the body of most of the microscopic
infusory animalcules, and which, by their incessant vibrations,
cause rapid movements. The sea-urchins and star-fishes
have little thread-like tubes issuing from eveiy side of the
body, furnished with a sucker at the end. By attaching
these to some fixed object, they are enabled to draw or roll
themselves along ; but their progress is always slow. In-
sects are distinguished for the great perfection of their or-
gans of motion. They have at least three pairs of legs, and
usually wings also. The Crustacea generally have at least
five pairs of legs, which are used for both swimming and
walking. The Worms are much less active ; some of them
have only short bristles at

their sides for locomotion ;
and even those that have
numerous feet, like the cen-
tipedes, are not distin-
guished for agility. Some Fig. 33.
of the marine species use their gills for paddles. (Fig. 33).

169. Among the Vertebrata, we find the greatest variety
of the organs and modes of locomotion, as well as the great-

58 ORGANS OF LOCOMOTION.

est perfection, whatever may be the element in which they
are exercised. The sailing of the eagle, the bounding of
the antilope, the swimming of the shark, are not equalled
by any movements of insects. This superiority is due to
the internal skeleton, which, while it admits a great display
of force, gives to the motions, at the same time, a great
degree of precision.

1. Plan of the Organs of Locomotion.

170. The organs of progression in vertebrated animals
never exceed four in number, and to them the term limits is
more particularly applied. The study of these organs, as
characteristic of the different groups of vertebrate animals, is
most interesting, especially when prosecuted with a view to
trace them all back to one fundamental plan, and to ob-
serve the modifications, oftentimes very slight, by which
a very simple organ is adapted to every variety of move-
ment. No part of the animal structure more fully illustrates
the unity of design or the skill of the Intellect which has
so adapted a single organ to such multiplied ends. On this
account, we propose to illustrate this subject somewhat in
detail.

171. It is easy to see that the wing which is to sustain
the bird in the air, must be different from the leg of the stag
which is made for running, or the fins of the fish that swims.
But, notwithstanding this diversity, the wing of the bird, the
leg of the stag, and the anterior fin of the fish, may
still be traced to the same plan of structure ; and if we
examine their skeletons, we find the same fundamental
parts. In order to show this, it is necessary to give a short
description of the composition of the arm or anterior ex-
tremity.

172. The anterior member, in the vertebrates, is invaria-
bly composed of the following bones ; 1. The shoulder-

ORGANS OF LOCOMOTION.

59

f

a.

\ I

\

Cd

Hade or scapula (a), a broad and flat bone, applied upon
the bones of the trunk ; 2. The arm (Z>), formed of a single
long cylindrical bone, the humerus ; 3. The fore arm, com-
posed of two long bones, the radius (c), and ulna (d),
which are often fused into one ; 4. The hand, which is
composed of a series of bones, more f.o

or less numerous in different classes,
and which is divided into three parts,
namely, the carpus or wrist (e), the
metacarpus or palm (f), and the
fingers (g). The clavicle or collar-
lone (o), when it exists, belongs also
to the anterior member. It is a
bone of a cylindrical form, fixed as
a brace between the breast-bone and
shoulder-blade. Its use is to keep the
shoulders separated ; to this end, we
find it fully developed in all ani-
mals which raise the limbs from the
sides, as the birds and the bats.
On the other hand, it is rudimentary,
or entirely wanting in animals which
move them backwards and forwards
only, as with most quadrupeds.

173. The following outlines will give an idea of the
modifications which these bones present, in different
classes. In the arm of man, (Fig. 34), the shoulder
blade is flat and triangular ; the bone of the arm is cylindri-
cal, and enlarged at its extremities ; the bones of the fore
arm are about the same length as the humerus, but more
slender ; the hand is composed of the following pieces,
namely, eight small bones of the carpus, arranged in two
ranks, five metacarpal bones, which are elongated, and

Fig. 34.

60

ORGANS OF LOCOMOTION.

succeed those of the wrist ; five fingers of unequal length,
one of which, the thumb, is opposed to the four others.

174. In the stag, (Fig. 35), the bones of the fore-arm
greatly prevail in length over that of the arm, and the radius
no longer turns upon the ulna, but is blended with it ; but it
is especially the metacarpal or cannon-bone, which is greatly
developed ; and being quite as long as the fore-arm, it is
apt to be mistaken for it. The fingers are reduced to two,
each of which is surrounded by a hoof, at its extremity.

175. In the arm of the lion, (Fig. 36), the arm bone is

Fig. 36.

stouter, the carpal bones are less numerous, and the fingers
are short, and armed with strong, retractile claws. In the
whale, (Fig. 37), the bones of the arm and fore arm are
much shortened and very massive ; the hand is broad, the
fingers strong, and distant from each other.
e

Fig. 38.

Fig. 39.

In the bat, (Fig. 38), the fingers, with the exception of the
thumb, which is represented by a small hook, are elongated
in a disproportionate manner, and across them the skin is

ORGANS OF LOCOMOTION.

61

stretched, so as to serve the purpose of a wing. In birds,
the pigeon, for example, (Fig. 39), there are but two fin-
gers, which are consolidated and destitute of nails ; and the
thumb is rudimentary.

176. The arm of the turtle (Fig. 40) is peculiar in hav-

a

d

Fisr. 41.

Fig. 42.

ing, besides the shoulder-blade, two clavicles ; the arm-bone
is twisted outwards, as well as the bones of the fore-arm, so
that the elbow, instead of being behind, is turned forwards;
the fingers are long and widely separated. In the Sloth
(Fig. 41), the bones of the arm and fore-arm are very
greatly elongated, and at the same time very slender ; the
hand is likewise very long, and the fingers are terminated
by enormous non-retractile nails. The arm of the mole,
(Fig. 42), is still more extraordinary. The shoulder-blade,
which is usually a broad and flat bone, becomes very
narrow ; the arm-bone, on the contrary, is contracted so
much as to seem nearly square ; and the hand is exces-
sively large and stout.

177. In fishes, the form and arrangement of the bones is
so peculiar that it is often difficult to trace their analogy to
all the parts found in other animals ; nevertheless, the
bones of the fore-arm are readily recognized. In the

6

62

ORGANS OF LOCOMOTION.

Cod, (Fig. 43), there are two flat and broad bones, one
of which, the ulna (rf), presents a long point, anteriorly.

Fig. 43.

The bones of the carpus are represented by four nearly
square little bones. But in these again, there are considera-
ble variations in different fishes, and in some genera they
are much more irregular in form. The fingers are but im-
perfectly represented by the rays of the fin (g), which are
composed of an infinitude of minute bones, articulated with
each other. As to the humerus and shoulder, their analo-
gies are variously interpreted by different anatomists.

178. The form of the members is so admirably adapted
to the special offices which they are designed to perform,
that by a simple inspection of the bones of the arm, as re-
presented in the preceding sketches, one might infer the uses
to which they were to be put. The arm of man, with its
radius turning upon its ulna, the delicate and pliable fingers,
and the thumb opposed to them, bespeak an organ for the
purpose of handling. The slender and long arm of the
sloth, with his monstrous claws, would be extremely incon-
venient for walking on the ground, but appropriate for seizing
upon the branches of the trees, on which these animals
live. The short fingers, armed with retractile nails, indicate
the lion, at first glance, to be a carnivorous animal. The
arm of the stag, with his very long cannon-bone, and that of
the horse also, with its single solitary finger enveloped in a
hoof, are organs especially adapted for running. The very
slender, and greatly elongated fingers of the bat are ad-
mirably contrived for the spread of a wing, without in-

ORGANS OF LOCOMOTION. 63

creasing the weight of the body. The more firm and solid
arm of the hird indicates a more sustained flight. The
short arm of the whale, with his spreading fingers, resem-
bles a strong oar. The enormous hand of the mole, with
its long elbow, is made for the difficult and long-continued
efforts requisite in burrowing. The twisted arm of the tor-
toise can be applied to no other purpose than creeping.
And finally, the arm of the fish, completely enveloped in
the mass of the flesh, presents, externally, a mere delicate
balancer, the pectoral fin.

179. The posterior members are closely analogous in
structure to the anterior. The bones of which they are
composed, are, 1. The pelvis, (Fig. 46), which corresponds
to the shoulder blade ; 2. The thigh bone or femur, which is
a simple bone like the humerus ; 3. The bones of the leg, the
tibia andjibula, which, like the radius and ulna, sometimes
coalesce into one bone ; and lastly, the bones of the foot,
which are divided, like those of the hand, into three parts,
the tarsus, metatarsus, and toes. The modifications are
generally less marked than in the arm, inasmuch as there is
less diversity of function ; for in all animals, without excep-
tion, the posterior extremities are used exclusively for walk-
ing or swimming.

180. The anterior extremity of the vertebrates, however

varied in form, whether it be an
arm, a wing, or a fin, is thus
shown to be composed of essen-
tially the same parts, and con-
structed upon the same general
plan. This affinity does not extend
to the invertebrates, although in
Fig. 44. Fig. 45. many instances their limbs bear

certain resemblance to those of the vertebrates, and are
even used for similar purposes, yet they have no real

64 OF STANDING AND PROGRESSION.

affinity. Thus the leg of an insect (Fig. 44), and that
of a lizard (Fig. 45) ; the wing of a butterfly and the
wing of a bat are quite similar in form, position and
use ; but in the bat and the lizard, the organ has an internal
bony support, which is a part of the skeleton ; while the
leg of the insect has merely a horny covering, proceeding
from one of the rings of the body, and the wing of the
butterfly is merely a fold of the skin ; showing that the limbs
of the Articulata are constructed upon a different plan
(157). It is by ascertaining and regarding these real affini-
ties, that the true natural grouping of animals is to be
attained.

2. Of Standing, and the Modes of Progression.

181. STANDING, or the natural attitude of an animal, depends
on the form and functions of the limbs. Most of the ter-
restrial mammals and the reptiles, both of which employ all
four limbs in walking, have the back-bone horizontal, and
resting at the same time upon both the anterior and posterior
extremities. Birds, whose anterior limbs are intended for a
purpose very different from the posterior, stand upon the
latter, when at rest, although the back-bone is still very
nearly horizontal. Man alone, is designed to stand upright,
with his head supported on the summit of the vertebral col-
umn. Some monkeys can rise upon the hind-legs into the
erect posture ; but it is evidently a constrained posture, and
not their habitual attitude.

182. That an animal may stand, it is requisite that the
limbs should be so disposed that the centre of gravity, in
other words, the point about which the body balances itself,
should fall within the space included by the feet. If the
centre of gravity is outside of these limits, the animal
falls to the side to which the centre of gravity inclines. On

OF STANDING. 65

this account, the albatross, and some other aquatic birds
which have the feet placed very far back, cannot use
them for walking.

183. The more numerous and the more widely separated
are the points of support, the firmer an animal stands. On
this account, quadrupeds are less liable to lose their balance
than birds. If an animal has four legs it is not necessary
that they should have a broad base. Thus we see that most
quadrupeds have slender legs touching the earth by only a
small surface. Broad feet would only increase the weight
of the limbs, without adding to their stability. Birds are
furnished with long toes, which, as they spread out, subserve
the purpose of tripods. Moreover, the muscles of the toes are
so disposed that the weight of the bird causes them to con-
tract firmly, so that it can sleep standing upon the roost
without effort, in perfect security.

Fig. 46.

184. In quadrupeds, the joints at the junction of the limbs
with the body bend readily in one direction only, that is, to-
wards the centre of gravity ; so that if one limb yields, the
tendency to fall is counteracted by the resistance of the limbs
at the other extreme of the body. The same antagonism
is observed in the joints of the separate limbs, which are
flexed alternately in opposite directions. Thus the thigh
bends forwards, and the leg backwards ; while the arm
bends backwards, and the fore-arm forwards. Different

66 MODES OF PROGRESSION.

terms have been employed to express the various modes of
progression, according to the rapidity or the succession in
which the limbs are advanced.

185. PROGRESSION is a forward movement of the body,
effected by successively bending and extending the limbs.
WALKING is the ordinary and natural gait, and other
paces are only occasionally employed. When walking
is accomplished by two limbs only, as in man, the body
is inclined forwards, and carries the centre of gravity in
that direction, and while one leg sustains the body, the
other is thrown forwards to prevent it from falling, and to
sustain it in turn. For this reason, walking has been de-
fined to be a continual falling forwards, continually inter-
rupted by the projection of the legs.

186. The throwing forwards of the leg, which would re-
quire a very considerable effort were the muscles obliged
to sustain the weight of the limbs also, is facilitated by a
very peculiar arrangement ; that is, the joints are perfectly
closed, so that the pressure of the atmosphere outside is
sufficient of itself to maintain them in place, without the
assistance of the muscles. This may be proved by experi-
ment. If we cut away all the muscles around the hip-joint,
the thigh-bone still adheres firmly to the pelvis, but sepa-
rates the moment a hole is pierced, so as to admit air into
the socket.

187. In ordinary walking, the advancing leg touches the
ground just before the other is raised ; so that there is a
moment when the body rests on both limbs. It is only when
the speed is very much accelerated, that the two actions be-
come simultaneous. The walking of quadrupeds is a simi-
lar process, but with this difference, that the body always
rests on two legs at least. The limbs are raised in a deter-
minate order, usually in such a manner that the hind-leg of
one side succeeds the fore-leg of the opposite side. Some

MODES OF PROGRESSION. 67

animals, as the giraffe, the lama, and the bear, raise both
legs of one side at the same moment. This is called
ambling or pacing.

188. RUNNING consists in the rapid repetition of the mo-
tions of walking. The running of lizards and birds is
merely an accelerated walk ; but in the horse and dog,
and most of the mammals, a distinction is made between the
walk, the trot, and the gallop, all of which have different
positions or measures. The trot has but two measures.
The animal raises a leg on each side, in a cross direction,
that is to say, the right fore leg with the left hind leg, and so
on. The gallop has three measures. After advancing the two
fore-legs, one after the other, the animal raises and brings
forward the two hind legs, simultaneously. Sometimes also,
when the gallop is greatly urged, there are but two mea-
sures ; the fore limbs are raised together, as well as the
hind legs.

189. LEAPING consists in a bending of all the limbs, fol-
lowed by a sudden extension of them, which throws the body
forwards with so much force as to raise it from the ground,
for an instant, to strike it again at a certain distance in
advance. For this purpose, the animal always crouches
before leaping. Most animals make only an occasional use
of this mode of progression, when some obstacle is to be
surmounted ; but in a few instances, this is the habitual
mode. As the hind legs are especially used in leaping, we
observe that all leaping animals have the posterior members
very much more robust than the anterior, as frogs, the kan-
garoos, jerboas, and even the hares. Leaping is also com-
mon among certain birds, especially among the sparro\vs,
the thrushes, &c. Finally, there is also a large number of
leaping insects, such as the flea, the large tribe of grass-
hoppers and crickets, in which we find that pair of legs
with which leaping is accomplished, much more developed
than the others.

68 MODES OF PROGRESSION.

190. CLIMBING- is merely walking upon the surface of an
inclined or even upright object. It is more frequently ac-
complished by means of sharp nails ; and hence many
carnivorous animals climb with great facility, such as the
cat tribe, the lizards ; and many birds, the woodpecker, for
instance. Others employ their arms for this purpose, like
the bears, when they climb a tree ; or their hands, and even
their tails, like the monkeys ; or their beaks, like the par-
rots. Lastly, there are some whose natural mode of pro-
gression is climbing. Such are the sloths, with their arms
so long, that when placed upon the ground, they move very
awkwardly ; and yet their structure is by no means defect-
ive, for in their accustomed movements upon trees, they
can use their limbs with very great adroitness.

191. Most quadrupeds can both walk, trot, gallop, and
leap ; birds walk and leap ; lizards neither leap nor gallop,
but only walk and run, and some of them with great rapid-
ity. No insect either trots or gallops, but many of them
leap. Yet their leaping is not always the effect of the mus-
cular force of their legs, as with the flea and grasshopper ;
but some of them leap by means of a spring, in the form of
a hook, attached to the tail, which they bend beneath the
body, and which, when let loose, causes them to bound to a
great distance, as in the Podurellse. Still others leap by
means of a spring, attached beneath the breast, which
strikes against the abdomen when the body is bent ; as the
spring-beetles (Elaters).

192. FLIGHT is accomplished by the simultaneous action
of the two anterior limbs, the wings, as leaping is by that of
the two hinder limbs. The wings being expanded, strike and
compress the air, which thus becomes a support, for the
moment, upon which the body of the bird may rest itself.
But as this support very soon yields, owing to the slight
density of the air, it follows that the bird must make the
greater and more rapid efforts to compensate for this dis-

MODES OF PROGRESSION. 69

advantage. Hence it requires a much greater expenditure
of strength to fly than to walk ; and therefore, we find the
great mass of muscles in birds concentrated about the
breast (Fig. 30). To facilitate its flight, the bird, after
each flap of the wings, brings them against the body, so as
to present as little surface to the air as possible ; for a
still further diminution of resistance, all birds have the
anterior part of the body very slender. Their flight
would be much more difficult if they had large heads
and short necks.

193. Some quadrupeds have a fold of the skin at the
sides, which may be extended by the legs, and which ena-
bles them to leap from branch to branch, with more facility,
such as the flying-squirrel and Galeopithecus. But this
is not flight, properly speaking, since none of the pecu-
liar operations of flight are performed. There are also
some fishes, whose pectoral fins are so extended as to ena-
ble them to dart from the water, and sustain themselves
for a considerable time in the air ; and hence they are
called flying-fish. But this is not truly flight.

194. SWIMMING is the mode of locomotion employed
by the greater part of aquatic animals. Most animals
which live in the water swim with more or less facility.
Swimming has this in common with flight, that the medium
in which it is performed, the water, becomes also the sup-
port, and readily yields also to the impulse of the fins.
Only, as water is much more dense than air, and as the
body of most aquatic animals is of very nearly the same
weight as water, it follows that in swimming, very little
effort is requisite to keep the body from sinking. The
whole effort of its muscles is consequently employed in pro-
gression, and hence swimming requires vastly less muscular
force than flying.

195. Swimming is accomplished by means of various or-

70 MODES OF PROGRESSION.

gans designated under the general term,j^?i5, although in an
anatomical point of view, these may represent very different
parts. In the Whales, it is the anterior extremities and
the tail which are transformed into fins. In Fishes, the pec-
toral fins, which represent the arms, and the ventral fins,
which represent the legs, are employed for swimming, but
they are not the principal organs ; for it is by the tail
or caudal fin, that progression is principally effected.
Hence the progression of the fish is precisely that of a
boat under the sole guidance of the sculling-oar. In the
same manner as a succession of strokes alternately right
and left, propels the boat straight forwards, so the fish
advances by striking alternately right and left. If he
wishes to advance obliquely, he has only to strike a little
more strongly in the direction opposite to that which he
wishes to take. The Whales, on the contrary, swim by
striking the water up and down ; and it is the same with a few
fishes also, such as the rays and the soles. The air-
bladder facilitates the rising and sinking of the fish by ena-
bling it to vary the specific weight of the body.

196. Most land animals swim with more or less ease, by
simply employing the ordinary motions of walking. Those
which frequent the water, like the beaver, or which feed on
marine animals, as the otter and duck, have webbed feet,
that is to say, the fingers are united by a membrane, which,
by being expanded, acts as a paddle.

197. There is also a large number of invertebrate ani-
mals in which swimming is the principal or the only mode
of progression. Lobsters swim by means of their tail, and
like the Whales, strike the water up and down. Other
Crustacea have a pair of legs fashioned like oars ; as
the posterior legs in Lupa, for example. Many insects,
likewise, swim with their legs, which are abundantly fringed
with hairs to give them surface ; as the little water boat-

MODES OF PROGRESSION.

71

men, (Gyrinus, Dytiscus), whose mazy dances on the sum-
mer streams every one must have observed. The cuttle-
fish uses its long tentacles as oars (Fig. 47) ; and some
star-fishes (Comatula, Euryale), use their arms with great
adroitness. Finally, there are some insects, which have
their limbs constructed for running on the surface of water,
as the water-spiders. (Ranatra, Hydrometra).

Pig. 47.

198. A large number of animals have the faculty of
moving both in the air and on land, as is the case with
most birds, and a large proportion of insects. Others move
with equal facility, and by the same members, on land and in
water, as some of the aquatic birds and most of the reptiles.
The latter have even received the name Amphibia, on this
account. Finally, there are some which both walk, fly
and swim, as the ducks and water hens ; but, on the other
hand, they do not excel in either mode of progression.

199. However different may appear to us the movements
and offices performed by the limbs, according to the element
in which they act, we see that they are none the less the
effect of the same mechanism. The contraction of the
same set of muscles, causes the leg of the stag to bend for
leaping, the wing of the bird to flap in the air, the arm of
the mole to excavate the earth, and the fin of the whale
to strike the water.

CHAPTER SIXTH.

NUTRITION.

200. THE second class of the functions of animal life
are those which relate to the maintenance of life and the
perpetuation of the species ; the functions of vegetative
life (59).

201. The increase of the volume of the body must re-
quire additional materials. There is also an incessant waste
of particles which, having become unfit for further use,
are therefore carried out of the system. Every contraction
of a muscle expends the energy of some particles, whose
place must be supplied. These supplies are derived from
every natural source, the animal, vegetable, and even the
mineral kingdoms ; and are received under every variety of
solid, liquid, and gaseous form. Thus, there is a perpetual
interchange of substance between the animal body and the
world around. The conversion of these supplies into a
suitable material, and the appropriation of it to the growth
and sustenance of the body, is called NUTRITION.

202. In early life, during the period of growth, the
amount of substances received is greater than that which is
lost. At a later period, when growth is completed, an equi-
librium between the matters received and those rejected, is
established. At a still later period, the equilibrium is again
disturbed, more is rejected than is retained, decrepitude be-
gins, and at last the organism becomes exhausted, the func-
tions cease, and death ensues.

OF DIGESTION.

73

203. The solids and fluids taken into the body as food
are subjected to a process called Digestion, by which the
solid portions are also reduced to a fluid state, the nutritive
separated from the excrementitious, and the whole is pre-
pared to become blood, bone, muscle, &c. The residue
is afterwards expelled, together with those particles of the
body which require to be renewed, and those \vhich have
been derived from the blood by several processes, termed
Secretions. Matters in a gaseous form are also received
and expelled with the air we breathe, by a process
called Respiration. The nutritive fluids are conveyed
to every part of the body by currents, usually confined in
vessels, and which, as they return, bring back the particles
which are to be either renovated or expelled. This circuit
is what is termed the Circulation. The function of Nutri-
tion, therefore, combines several distinct processes.

SECTION T.

OF DIGESTION.

204. DIGESTION, or the process by which the nutritive
parts of food are elaborated and

prepared to become blood, is ef-
fected in certain cavities, the stom-
ach and intestines, or alimentary
canal. This canal is more or less
complicated in the various classes
of animals ; but there is no animal,
however low its organization, which
has not a stomach, (54).

205. In the polypi, the digestive

apparatus is limited to a single cav- Fig. 48.

ity. In the Sea Anemone (Actinia), for example, it is a
pouch (Fig. 48, b), suspended in the interior of the body.

7

74

NUTRITION.

When the food has been sufficiently digested there, it passes
into the general cavity of the body (c), which is filled with
water, and mingling with it, flows thence into all parts

of the animal. The jelly-fishes (Medusse),
and some Worms have a distinct stomach,
with appendages branching off in every di-
rection (Fig. 31), in which a more com-
plete elaboration takes place. The little
worms known by the name of Planaria
present a striking example of these rami-
fications of the intestine (Fig. 49, e). But
here likewise, the product of digestion,
namely, the chyle, mingles with the fluids
of the cavity of the body which surround
the intestine (d] and its branches, and cir-
culation is not yet distinct from diges-

Fig. 49. tion.
206. As we rise in the scale of animals, the functions
concerned in nutrition become more and more distinct from
each other. Digestion and circulation, no longer confounded,
are accomplished separately, in distinct cavities. The most
important organs concerned in di-
gestion are the stomach, and the
small and large intestine. The
first indications of such a distinc-
tion are perceived in the higher
Radiata, such as the sea-urchins
(Fig. 50), in which the stomach (s),
is broader than either extremity of
the intestine. The dimensions and
form of the intestinal cavities vary Fig. so.

considerably according to the mode of life of the animal ;
but the special functions assigned to them are invariable ;
and the three principal cavities succeed each other, in every
animal where they are found, in an invariable order ; first,

J

OF DIGESTION.

75

the stomach (5), then the intestine, which is small at first,

but often enlarged to-
wards its termination.
This arrangement may
be seen by the following
diagrams from a beetle,
and a land-mollusk, where
the same letters indicate
corresponding parts (Figs.
51, 52).

207. From the mouth,
the food passes into the
stomach through a narrow
tube in the neck, called
the cesophagus or gullet
(o). This is not always a

Fisr. 51.

Fig. 52.

direct passage of uniform size ; but there is sometimes a
pouch, the crop (c), into which the food is first introduced,
and which sometimes acquires considerable dimensions, espe-
cially in birds, and in some insects andmollusks (Fig. 51). In
the stomach, the true digestive process is begun. The food no
sooner arrives there than changes commence, under the influ-
ence of a peculiar fluid called the gastric juice, which is se-
creted by the glands lining the interior of the stomach. The
digestive action is sometimes aided by the movements of
the stomach itself, which, by its strong contractions, tritu-
rates the food. This is especially the case in the gizzard
of some birds, which, in the hens and ducks, for instance, is
a powerful muscular organ. In some of the Crustacea and
Mollusks, as the Lobster and Aplysia, there are even solid
organs for breaking down the food within the stomach itself.
208. The result of this process is the reduction of the
food to a pulpy fluid called chyme, which varies in its
nature with the food. Hence the function of the stomach
has been named chymification. The chyme thus formed

76

NUTRITION.

is transferred to the intestine, by a peculiar movement like
that of a worm in creeping, which has accordingly received
the name of vermicular or peristaltic motion.

209. The form of the small intestine is less variable than
that of the stomach. It is a narrow tube with thin walls,
coiled in various directions in the vertebrate animals, but
more simple in the invertebrates, especially the insects. Its
length varies according to the nature of the food, being in
general longer in herbivorous than in carnivorous animals.
In this portion of the canal, the aliment undergoes its
complete elaboration, through the agency of certain juices
which here mingle with the chyme, such as the bile secreted
by the liver, and the pancreatic juice secreted by the
pancreas. The result of this elaboration is to produce a
complete separation of the truly nutritious parts, in the
form of a milky liquid called chyle. The process is called
chylification.

210. The chyle is composed of minute, colorless globules,

of a somewhat flattened form (Fig. 53). It
is taken up and carried into the blood by
means of very minute vessels, called lym-
\phatic vessels or lacteals, which are distri-
buted everywhere in the walls of the intestine,
and communicate with the veins, forming also
in their course several glandu-
lar masses, as seen on the por-
tion of intestine connected with a
vein (Fig. 54). The residue
passes on to the large intestine,
from whence it is expelled in
the form of excrement.

211. These organs constitute
the essential apparatus for diges-
. 54. tion ; but there are, in the higher

animals, several additional ones for aiding in the reduction of

Fig. 53.

OF DIGESTION.

77

the food to chyle which render their digestive apparatus
quite complicated. In the first place, hard parts, of a horny
or bony texture, are usually placed ahout the mouth of
those animals that feed on solid substances, which serve
for cutting or bruising the food into small fragments before
it is swallowed ; and, in many of the lower animals, these
organs are the only hard portions of the body. This pro-
cess of subdividing or chewing the food, is termed masti-
cation.

212. Beginning with the Radiata, we find the apparatus
for mastication partaking of the star-like arrangement which

Fig. 55. Fig. 56.

characterizes those animals. Thus, in Scutella (Fig. 55),
we have a pentagon composed of five triangular jaws, con-
verging at their summits towards a central aperture which
corresponds to the mouth, each one bearing a plate or tooth,
like a knife-blade, fitted by one edge into a cleft. The five
jaws move towards the centre, and pierce or cut the objects
which come between them. In some of the sea-urchins,
(Echinus), this apparatus, which has been called Aristotle's
lantern (Fig. 56), consists of numerous pieces, and is
much more complicated. Still, the five fundamental pieces
or jaws, each of them bearing a tooth at its point, may be
recognized as in Scutella ; only instead of being placed hori-
zontally, they form an inverted pyramid.

7*

78

NUTRITION.

213. Among the Mollusks, a few, like the cuttle-fishes,
have solid jaws or beaks closely resem-
bling the beak of a parrot
(Fig. 57) ; and they move
up and down as in birds.
But a much larger number

\

rasp their food by means of
a tongue coiled like a watch-

Fig. 58.

Fig. 57.

spring, the surface of which is covered with innumerable
minute tooth-like points of a horny consistence, as in the
highly magnified portion of the tongue of Natica (Fig. 58).
214. The Articulata are remarkable, as a class, for the
diversity and complication of their apparatus for taking and

dividing their food. In some marine worms,
Nereis, for example, the jaws consist of a
pair of curved, horny instruments, lodged in
a sheath (Fig. 59). In spiders, these jaws
are external, and sometimes mounted on
Fig. 59. long, jointed stems. Insects which masti-
cate their food have, for the most part, at least two pairs
of horny jaws (Fig. 60, 61, w), besides several additional
pieces which serve for seizing and holding their food.
Those which live on the fluids which they extract either
from plants or from the blood of other animals, have the
masticatory organs transformed into a trunk or tube for this
purpose. This trunk is sometimes rolled up in a spiral
manner, as in the butterfly (Fig. 64) ; or it is stiff, and

\

V

Fig. 61. Fig. 62. Fig. 63.

Fig. 64.

folded beneath the chest, as in the squash-bugs (Fig. 62),

OF DIGESTION.

79

and contains several piercers of extreme delicacy, (Fig. 63),
adapted to penetrate the skin of animals or other objects
whose juices they extract ; or they are prolonged so as to
shield the tongue when thrust out in search of nutritive
juices, as in the bees (Fig. 61.) The crabs have their
anterior feet transformed into a kind of jaws. Indeed,
even down to the microscopic Rotifers, we find veiy
complicated jaws, as seen in the interior of Brachionus

Fig. 65.

Fig. 66.

(Fig. 65), and represented largely magnified in Fig. 66.
But amidst this diversity of apparatus, there is one thing
which characterizes all the Articulata, namely, the jaws all
move sideways ; while those of the Vertebrates move up and
down, and those of the Radiata move concentrically.

215. In the Vertebrates, the jaws form a part of the bony

skeleton. In most of them the
lower jaw only is movable, and
is brought up against the upper
'jaw by means of very strong mus-
cles, the temporal and masseter
Fig. 67. muscles (Fig. 67, £, m), which per-

form all the motions requisite for seizing and masticating food.

216. The jaws are usually armed
with solid cutting instruments, the
TEETH, or else enveloped in a horny
covering, the leak, as in the birds and
tortoises (Fig. 68). In some of the

whales, we have instead, a range of Fig. 68.

80

NUTRITION.

long, flexible, horny plates or fans, fringed at the margin,
which serve as strainers to separate the minute marine ani-
mals on which they
feed, from the water
drawn in with them
(Fig. 69). A few are
entirely destitute of
teeth, as the ant-eater
(Fig. 70).

217. Though all the
Fig. 69. vertebrates possess jaws,

it must not be inferred that they all chew their food.
Many of them swallow their prey whole ; as most birds,
tortoises, and whales. Even those which are furnished
with teeth do not all of them masticate their food ; some
use them merely for seizing and securing their prey, as
we find in the lizards, frogs, crocodiles and the great
majority of fishes. In such animals, it has been remarked
that the teeth are nearly all alike in form and structure, as

Fisr. 71.

Fig. 72.

for instance in the alligator (Fig. 71) ; and in most fishes.
A few of the latter, some of the Rays, for example, have
a sort of bony pavement (Fig. 72), composed of a peculiar

OF DIGESTION.

81

kind of teeth, with which they crush the shells of the
mollusks on which they feed.

218. The Mammals, however, are almost the only verte-
brates which can be properly said to masticate their food.
Their teeth are well developed, and present great diversity
in form, arrangement and mode of insertion. Three kinds
of teeth are usually distinguished in most of these ani-
mals, whatever may
be their mode of life ;
namely, the cutting
teeth, incisors ; the
tusks or carnivorous
teeth, canines ; and
the grinders, molars
(Fig. 73). The in-
cisors (a) occupy the
front of the mouth ;
they are the most simple and the least varied ; they have
a thin cutting summit, and are employed almost exclu-
sively for seizing food ; except in the elephant, in which
they assume the form of large tusks. The canines (b) are
conical, more prominent than the others, more or less
curved, and only two in each jaw. They have but a single
root, like the incisors, and in the carnivora become very
formidable weapons. In the herbivora, they are entirely
wanting, or when existing they are so enlarged and modi-
fied as also to become powerful organs of offence and
defence, although useless for mastication ; as in the baby-
roussa, &c. The molars (c) are the most important for
indicating the habits and internal structure of the animal ;
and at the same time they are most varied in shape.
Among them we find every transition, from those of a
sharp and pointed form, as in the cat tribe, to those with
broad and level summits, as in the ruminants and rodents.

Fig. 73.

82

NUTRITION.

Still, they have one constant character, namely, their roots
are never simple, but double or triple, which not only
fixes them more firmly, but prevents them from being
driven into the jaw in the efforts of mastication.

219. The harmony of organs already spoken of (22 -24)
is illustrated, in a most striking manner, by the study
of the teeth of the mammals, and especially of their molar
teeth. So constantly do they correspond with the struc-
ture of the other parts of the body, that a single molar
is sufficient not only to indicate the mode of life of the ani-
mal from which it was obtained, and to show whether it
fed on flesh or vegetables, but also to determine the particu-
lar group to which it belongs. Thus, those beasts of prey
which feed on insects, and which on that account have been

Fig. 74.

Fig. 76. Fig. 75.

called Insectivora, such as the moles and bats, have the mo-
lars terminated by several sharp, conical points (Fig. 74),
so arranged that the elevations of one tooth fit exactly into
the depressions of the tooth opposite to it. In the true Car-
nivora (Fig. 75), on the contrary, the molars are com-
pressed laterally, so as to produce a sharp cutting edge ;
and they shut by the side of each other, like the blades of
scissors, thereby dividing the food with great facility.

220. The same adaptation is observed in the teeth of
herbivorous animals. Those which chew the cud (rumi-
nants), many of the thick skinned animals (pachydermata),

OF DIGESTION. 83

like the elephant, and some of the gnawers (rodentia),
like the hare (Fig. 76), have the summits of the molars
flat, like millstones, for grinding the grass and leaves
on which they subsist. Finally, the omnivora, those which
feed on both flesh and fruit, like man and the monkeys,
have the molars terminating in several rounded tubercles,
being thus adapted to the mixed nature of their food.

221. Again, the mode in which the molars are combined
with the canines and incisors furnishes excellent means of
characterizing families and genera. Even the minute struc-
ture of a tooth is so peculiar in each group of animals,
and yet is subject to such invariable rules, that it is possible
to decide positively the structure of an animal, merely by
the inspection of the fragment of a tooth under the micro-
scope.

222. Another process, subsidiary to digestion, is called
insalivation. Animals which masticate their food have
glands, in the neighborhood of the mouth, which secrete a
fluid called saliva. This fluid mingles with the food as it is
chewed, and prepares it also to be more readily swallowed.
The salivary glands are wanting in all animals which swal-
low their food without mastication. When the food is mas-
ticated and mingled with saliva, it is carried back by
the tongue, and passes down a tube, the oesophagus, into
the stomach. This act is called deglutition or swal-
lowing.

223. The wisdom and skill of the Creator is strikingly illus-
trated in the means he has afforded to every creature for se-
curing the means of its subsistence. Some animals have no
ability to move from place to place, but are fixed to the soil ;
as the oyster, the polypi, &c. These are dependent for sub-
sistence upon such food as may stray or float near, and they
have the means of securing it when it comes within their
reach. The oyster closes its shell, and thus secures its prey ;

84 NUTRITION.

the polyp has flexible arms (Fig. 77), capable of great exten-
sion, which instantly embrace any minute ani-
mal that comes in contact with them. The
cuttle-fish also, has similar arms about the
mouth, furnished with ranges of suckers, by
which it secures its prey (Fig. 47).

224. Some are provided with instruments
for extracting food from places which would

be otherwise inaccessible. Some of the Fig. 77.
mollusks, with their rasp-like tongue (Fig. 58), perforate
the shells of other animals, and thus reach and extract
the inhabitant. Insects have various piercers, suckers, or a
protractile tongue for the same purpose (Figs. 61-64).
Many of the Annelides, the leeches for example, have a
sucker, which enables them to produce a vacuum, and
thereby draw out blood from the perforations they make.
Many microscopic animals are provided with hairs or cilia
around the mouth (Fig. 65), which by their incessant
motion produce currents that bring within reach the
still more minute creatures or particles on which they
feed.

225. Among the Vertebrata, the herbivora generally
employ their lips or their tongue, or both together, for seiz-
ing the grass or leaves they feed upon. The carnivora
use their jaws, teeth, and especially their claws, which
are long, sharp and movable, and admirably adapted for
the purpose. The woodpeckers have long, bony tongues,
barbed at the tip, with which they draw out insects from
deep holes and crevices. Some reptiles also use their
tongue to take their prey. Thus, the chameleon obtains
flies at a distance of three or four inches, by darting out
his tongue, the enlarged end of which is covered with a
glutinous substance to which they adhere. The elephant,
whose tusks and short neck prevent him from bringing his

OF DIGESTION. 85

mouth to the ground, has the nose prolonged into a trunk,
which he uses with great dexterity, for bringing food and
drink to his mouth. Doubtless the mastodon, once so abun-
dant in this country, was furnished with a similar organ.
Man and the monkeys employ the hand exclusively, for
prehension.

226. Some animals drink by suction, like the ox, others
by lapping, like the dog. Birds simply fill the beak with
water, then raising the head, allow it to run down into the
crop ; some of them, however, suck up liquids, like the
herbivora.

6

CHAPTER SEVENTH.

OF THE BLOOD AND CIRCULATION.

227. THE nutritive portions of the food are poured into
the blood or the general mass of fluid which pervades every
part of the body, and out of which every tissue is origi-
nally constructed, and from time to time renewed.

228. The Blood, when examined by the microscope, is
found to consist of a transparent fluid, the serum, in which
float many rounded, somewhat compressed bodies, called
globules. These globules vary in number with the natural
heat of the animal from which the blood is taken. Thus,
they are more numerous in birds than in the mammals, and

Fig. 79.

Fig. 80.

Fig. 81.

Fig. 78.

more abundant in the latter than in fishes. In man and
other mammals they are very small and nearly circular
(Fig. 78) ; they are somewhat larger and of an oval form
in birds and fishes (Figs. 79, 81) ; and still larger in rep-
tiles (Fig. 80).

229. The color of the blood in the vertebrates is bright
red ; but in some invertebrates, as in the crabs and mol-
lusks, it is nearly or quite colorless ; while in the worms

OF THE BLOOD AND CIRCULATION. 87

and some echinoderms, it is variously colored yellow,
orange, red, violet, lilac, and even green.

230. The presence of this fluid in every part of the
body is one of the essential conditions of animal life. A
perpetual current flows from the digestive organs towards
the remotest parts of the surface ; and such portions as are
not required for nutriment return, mingled with those which
have become useless and need to be renewed or expelled.
The blood is kept in an incessant CIRCULATION for this
purpose.

231. In the lowest animals, such as the polypi, the nutri-
tive fluid is merely the products of digestion mingled with
water in the common cavity of the viscera, with which it
comes in immediate contact, as well as with the whole
interior of the body. In the jelly-fishes, which occupy a
somewhat higher rank, a similar liquid is distributed by pro-
longations of the principal cavity to different parts of the
body (Fig. 31). Currents are produced in these, partly by
the general movements of the animal, and partly by means
of the incessant vibrations of microscopic hairs which over-
spread the interior, and are hence called vibratile cilia. In
most of the mollusks and insects, the blood is also in imme-
diate contact with the viscera ; or the vessels, if any, are
not continuous, but terminate in various cavities.

232. In animals of still higher organization, as the verte-
brates, the mollusks, and a part of the articulata and
echinoderms, we find the vital fluid enclosed in an appro-
priate set of vessels, by which it is successively con-
veyed throughout the system to supply its wants, and to the
respiratory organs, where it absorbs oxygen, or in other
words, becomes oxygenated.

233. The vessels in which the blood circulates are of
two kinds : 1. The arteries, of a firm, elastic structure,
which may be distended or contracted, according to the

88 OF THE BLOOD

volume of their contents, and which convey the blood from
the centre towards the surface, distributing it to every
point of the body ; 2. The veins, of a thin, mem-
branous structure, furnished within with valves,
(Fig. 82, v), which aid in sustaining the column
of blood, and allow it to flow towards the
centre only. The arteries constantly subdivide
into smaller and smaller branches ; while the
veins commence in minute twigs, and are gath-
ered into branches and larger trunks to unite final-
ly at the centre.

234. The extremities of the arteries and veins are con-

r +. nected by a net-work of extremely
iff minute and delicate vessels, called
£ capillary vessels (Fig. 83). They
77 pervade every portion of the body,
so that almost no point can be pricked
Fig. 83. from which blood will not issue.

Notwithstanding their minuteness, the most important pro-
cesses of nutrition are performed by these vessels, such as
the removal of effete particles and the substitution of new
ones, and all those changes by which the bright blood of the
arteries becomes the dark blood of the veins ; and again, in
the capillaries of the respiratory organs, the dark venous
blood is oxygenated and restored to the bright scarlet hue of
the arterial blood.

235. Where there are blood-vessels in the lowest animals
the blood is kept in motion by

the occasional contraction of

some of the principal vessels, as

in the worms. Insects have a

large vessel running along the

back, furnished with valves so

arranged that, when the vessel pig. 34.

contracts, the blood can flow only towards the head, and

i

AND CIRCULATION.

89

being thence distributed to the body, is returned again into
the dorsal vessel (Fig. 83), by fissures at its sides.

236. In all the higher animals there is a central organ,
the heart, which forces the blood through the arteries to-
wards the surface, and receives it again on its return.
The HEART is a hollow muscular organ of a conical
form, which dilates and contracts at regular intervals, inde-
pendently of the will. It is either a single cavity, or is di-
vided by walls into two, three, or four compartments, as
seen in the following diagrams. These modifications are
important in their connection with the respiratory organs, and
indicate the higher or lower rank of an animal, as determined
by the quality of the blood distributed in those organs.

237. In the mammals and birds the heart is divided by
a vertical partition into two cavities, each of which is
again divided into two compartments, one above the other
(Fig. 85). The two upper cavities are called auricles, and
the lower ones are called ventricles. Reptiles have two

Fig. 85.

Fig. 86.

Fig. 87.

auricles and one ventricle (Fig. 86). Fishes have one auri-
cle and one ventricle only (Fig. 87).

238. The auricles do not communicate with each other,
nor do the ventricles. The former receive the blood
from the body and from the respiratory organs, and each
auricle sends it into the ventricle beneath, through an
opening guarded by a valve, to prevent its reflux ; while
the ventricles, by their contractions, force the blood through
the arteries into the lungs and through the body generally.

8*

DO OF THE BLOOD

239. The two auricles dilate at the same instant, and also
contract simultaneously ; so also do the ventricles. These
successive contractions and dilatations constitute the pul-
sations of the heart. The contraction is called systole,
and the dilatation is called diastole. Each pulsation con-
sists of two movements, the diastole or dilatation of the
ventricles, during which the auricles contract, and the systole
or contraction of the ventricles, while the auricles dilate.
The frequency of the pulse varies in different animals, and
even in the same animal, according to age, sex, and the de-
gree of health. In adult man, they are commonly about
seventy beats per minute.

240. The course of the blood in those animals which
have four cavities to the heart is as follows, beginning with
the left ventricle (Fig. 85, lv}. By the contraction of this
ventricle, the blood is driven through the main arterial
trunk, called the aorta (Fig. 90, a), and is distributed by its
branches throughout the body ; it is then collected by the
veins, carried back to the heart, and poured into the right
auricle (Fig. 85, ra), which sends it into the right ventricle
(rv). The right ventricle propels it through another set of
arteries, the pulmonary arteries (Fig. 90, p), to the lungs (Z) ;
it is there collected by the pulmonary veins, and conveyed
to the left auricle (Fig. 85, la), by which it is returned to the
left ventricle, thus completing the circuit.

241. Hence the blood in performing its whole circuit
passes twice through the heart. The first part of this cir-
cuit, the passage of the blood through the body, is called
the great circulation ; and the second part, the passage
of the blood through the lungs, is the lesser or pulmonary
circulation : this double circuit is said to be a complete
circulation. In this case the heart may be justly re-
garded as two hearts conjoined, and in fact the whole of
the lesser circulation intervenes in the passage of the blood

AND CIRCULATION. 91

from one side of the heart to the other ; except during the
embryonic period, when there is an opening between the
two auricles, which closes as soon as respiration commences.

242. In reptiles (Fig. 86), the venous blood from the body
is received into one auricle, and the oxygenated blood from
the lungs into the other. These throw their contents into the
single ventricle below, which propels the mixture in part to
the body, and in part to the lungs ; but as only the smaller
portion of the whole quantity is sent to the lungs in a
single circuit, the circulation is said to be incomplete. In
the Crocodiles, the ventricle has a partition which keeps
separate the two kinds of blood received from the auricles ;
but the mixture soon takes place by means of a special
artery which passes from the pulmonary artery to the aorta.

243. In fishes (Fig. 87) the blood is carried directly from
the ventricle to the gills, which are the respiratory organs ;
whence it passes into the arteries for distribution to the sys-
tem in general, and returns by the veins to the auricle.
Here the blood, in its circuit, passes but once through the
heart ; but the heart of a fish corresponds nevertheless to
the heart of a mammal, and not to one half of it, as has
often been maintained.

244. Crabs and other Crustacea have but a single ventri-
cle without an auricle.

In the mollusks there is
likewise but a single
ventricle, as in Natica
(Fig. 88, h). Some have
in addition one or two
auricles. These auricles
are sometimes so dis- Fi£- 88'

joined as to form so many isolated hearts, as in the cuttle-
fish. Among Radiata, the sea-urchins are provided with
a tubular heart.

CHAPTER EIGHTH.

OF RESPIRATION.

245. FOR the maintenance of its vital properties, the
blood must be submitted to the influence of the air. This
is true of all animals, whether they live in the atmosphere
or in the water. No animal can survive for any considera-
ble period of time without air ; and the higher animals
almost instantly die when deprived of it. It is the office of
RESPIRATION to bring the blood into communication with
the air.

246. Among animals which breathe in the open
air, some have a series of tubes branch-
ing through the interior of the body,

called trachece (Fig. 89, £), and opening
externally upon the sides of the body,
by small apertures, called stigmata (s) ; as
in the insects and in some spiders. But
the most common mode of respiration is
by means of the LUNGS, a pair of peculiar
spongy or cellular organs, in the form
of large pouches, which are the more
complicated in proportion to the quantity
of air to be consumed.

247. In the lower vertebrata provided with lungs there is
a single organ ; but in the higher classes they are in pairs,
placed in the cavity formed by the ribs, one on each side of

Fig. 89.

OF RESPIRATION.

93

Fig. 90.

the vertebral column, and enclosing the heart (h) between
them (Fig. 90, / Z). The lungs communicate with the atmo-
sphere by means of a tube composed of cartilaginous
rings which arises from the back part of the mouth, and
divides below, first into a branch for each organ, and then
into innumerable branches penetrating
their whole mass, and finally termina-
ting in minute sacs. This tube is the
trachea onvindpipe (w),and its branches
are the bronchi. In the higher air-
breathing animals the lungs and heart
occupy an apartment by themselves,
the chest, which is separated from the
other contents of the lower arch (161),
by a fleshy partition, called the dia-
phragm, passing across the cavity of the
body, and arching into the chest. The only access to this
apartment is by the glottis (Fig. 22, o) through the trachea.

248. The mechanism of respiration by lungs may be
compared to the action of a bellows. The cavity of the
chest is enlarged by raising the ribs, the arches of which
naturally slope somewhat downward, but more especially by
the contraction of the diaphragm, whereby its intrusion into
the chest is diminished. This enlargement causes the air to
rush in through the trachea, distending the lung so as to
fill the additional space. When the diaphragm is again re-
laxed, and the ribs are allowed to subside, the cavity is
again diminished, and the air expelled. These movements
are termed inspiration or inhalation, and expiration. The
spongy pulmonary substance being thus distended by air,
the blood sent from the heart is brought into such contact
with it as to allow the requisite interchange to take
place (235).

249. The respiration of animals breathing in water is ac-

94 OF RESPIRATION.

complished by a different mechanism. The air is to be

derived from the water, in which
more or less is always diffused.
The organs for this purpose are
91- called branchi<z or gills, and are

either delicate tufts or plumes floating outside of the body,
as in some of the marine worms
(Fig. 33), and many mollusks (Fig.
91, g] ; or they consist of deli-
cate folds, as in fishes (Fig. 92),
crabs and most mollusks (Fig. 88, g}.
These gills are always so situated
that the water has free access to Fig. 92.

them. In the lower aquatic animals, such as the polypi,
jelly-fishes and some mollusks, respiration is facilitated
by the incessant motions of vibratory cilia, which line
the respiratory organs as well as other portions of the sur-
face of the body ; the currents they produce bringing
constantly fresh supplies of water containing air in contact
with the respiratory organs.

250. Many animals living in water, however, rise to the
surface and breathe the atmosphere there, or are furnished
with the means of carrying away a temporary supply of air.
This is the case with the whale tribe, many insects and
mollusks.

251. The vivifying power of the air upon the blood is due
to its oxygen. If an animal be confined for a time in a
closed vessel, and the contained air be afterwards ex-
amined, a considerable portion of its oxygen will have
disappeared, and another gas of a very different character,
namely, carbonic acid gas, will have taken its place.
The essential office of respiration is to supply oxygen to
the blood, whereby also carbon is removed from it.

252. An immediately obvious effect of respiration in the

OF RESPIRATION. 95

red-blooded animals is a change of color. The blood in
passing through the respiratory organs, being changed from
a very dark purple to a bright scarlet. In the great circula-
tion (241) the scarlet blood occupies the arteries, and is usu-
ally called red Hood, in contradistinction from the venous
blood, which is called Hack Hood. In the lesser circulation,
on the contrary, the arteries carry the dark, and the veins
the red blood.

253. The quantity of oxygen consumed by various ani-
mals in a given time has been accurately ascertained by
experiment. It has been found, for instance, that a common-
sized man consumes, on an average, about 150 cubic feet in
twenty-four hours ; and as the oxygen constitutes but 21 per
cent, of the atmosphere, it follows that he inhales, during a
day, about 700 cubic feet of atmospheric air. In birds, the
respiration is still more active, while in reptiles and fishes it
is much more sluggish.

254. The energy and activity of an animal correspond
with the activity of its respiration. Thus the toad, whose
movements are very sluggish, respires much more slowly
than the mammals, birds, and even insects ; and it has been
ascertained that a butterfly, notwithstanding its comparatively
diminutive size, consumes more oxygen than a toad.

255. The circulation and respiration have a reciprocal in-
fluence upon each other. If the heart be powerful, or if
violent exercise demand a more rapid supply of blood to
repair the consequent waste (201), respiration must be
proportionally accelerated to supply air to the greater
amount of blood sent to the lungs. Hence the panting
occasioned by running or other unusual efforts of the
muscles. On the other hand, if respiration be hurried, the
blood being rendered more stimulant by greater oxygena-
tion, causes an acceleration of the circulation. The quan-
tity of air consumed varies therefore with the proportion of
the blood which is sent to the lungs.

96 OF RESPIRATION.

256. The proper temperature of an animal, or what is
termed ANIMAL HEAT, depends on the combined activity of
the respiratory and circulating systems, and is in direct pro-
portion to it. In many animals the heat is maintained at a
uniform temperature, whatever may be the variations of
the surrounding medium. Thus, birds maintain a tempera-
ture of about 108° Fahrenheit ; and in a large proportion
of mammals it is generally from 95° to 105°. These bear
the general designation of warm-Hooded animals.

257. Reptiles, fishes, and most of the still lower animals,
have not this power of maintaining a uniform temperature.
The heat of their body is always as low as from 35° to 50°,
but varies perceptibly with the surrounding medium, being
however, often a little above it when the external tempera-
ture is very low, though some may be frozen without the
loss of life. For this reason they are denominated cold-
Hooded animals ; and all of them have such a structure of
the heart, that only a part of the blood which enters it is
sent to the respiratory organs (243).

258. The production of animal heat is obviously con-
nected with the respiratory process. The oxygen of the
respired air is diminished, and carbonic acid takes its
place. The carbonic acid is formed in the body by the
combination of the oxygen of the air with the carbon of
the blood. The chemical combination attending this func-
tion is therefore essentially the same as that of combustion.
It is thus easy to understand how the natural heat of an animal
is greater, in proportion as respiration is more active. How
far nutrition in general, and more particularly assimilation,
by which the liquid parts are fixed and solidified, is con-
nected with the maintenance of the proper temperature of
animals, and its uniform distribution through the body, has
not yet been satisfactorily ascertained.

259. Some of the higher warm-blooded animals do not

OF RESPIRATION. 97

maintain their elevated temperature during the whole year ;
but pass the winter in a sort of lethargy called HIBERNATION,
or the hibernating sleep. The marmot, the bear, the bat,
the crocodile and most reptiles, furnish examples. During
this state the animal takes no food ; and as it respires only
after very prolonged intervals, its heat is diminished, and its
vital functions generally are much reduced. The structural
cause of hibernation is not ascertained ; but the phenomena
attending it fully illustrate the laws already stated (254-8).
260. There is another point of view in which respiration
should be considered, namely, with reference to the specific
gravity of animals, or their power of rising in the atmo-
sphere, and of living at different depths in the water, under
a diminished or increased pressure. The organs of respira-
tion of birds and insects are remarkably adapted for the pur-
pose of admitting at will a greater quantity of air into their
body, the birds being provided with large pouches extending
into the abdominal cavity and into the bones of the wing ;
whilst in insects the whole body is penetrated by air tubes
enlarged at intervals into wider cells. Aquatic animals are
all provided with minute, almost microscopic water-tubes,
penetrating from the surface into their substance, or
the cavity, by which the body is adapted to pressures
which otherwise would crush the animal. In fishes, these
water-tubes penetrate through the bones of the skull, and
through skin and scales; in mollusks they are more nu-
merous in the fleshy parts, as for example, in the foot ;
in echinoderms they pass through the skin, and even
through the hard shell, whilst in polyps they perforate the
walls of the general cavity of the body.

9

CHAPTER NINTH.

OP THE SECRETIONS.

261. WHILE the body is assimilating foreign substances
for its nutrition and growth, it is also freeing itself from
other substances which have become useless (201). The
different processes for effecting this latter object are called
SECRETIONS.

262. In this operation the skin is largely concerned. Be-
ing the outermost envelop of the body, and designed to pro-
tect it from external influences, it is the seat of continual
loss and reparation. New membranes and new tissues are
constantly forming, while the old ones are removed. This
removal is sometimes gradual and continual, in the form of
slime, as in the fishes and most of the mollusks, their mucus
being in fact a collection of cells detached from the surface
of the skin ; and sometimes periodical, when it constitutes
moulting. Thus, the mammals cast their hair, the birds
their feathers, the serpents their outer skin, the crabs their
test, the caterpillars their outer envelop with the hairs arising
from it.

263. We shall hereafter see that the skin presents such
varieties of composition in the different groups of the Ani-
mal Kingdom as to furnish excellent distinctions for species,
genera, and even families. In the vertebrates it is com-
posed of three very distinct layers of unequal thickness, as

OF THE SECRETIONS. 99

may be seen by Fig. 94, which represents a magnified sec-
tion of the human skin traversed by the sudoriferous canals.
The lower layer or the leather (a) is the thickest ; it covers
the muscles, from which it is separated by a bed of fat
in which the glands of transpiration are situated. Above the
leather is a thinner layer, the vascular layer (Z»), so called
from the abundance of blood vessels it contains ; it is also
traversed by numerous nerves, which render it very sensi-
tive. The third or superficial layer is called epidermis (c).
It contains neither nerves nor blood vessels, and conse-
quently is insensible. The scales of reptiles, the nails of
mammals, and the solid envelops of the Crustacea are merely
indurated products of the epidermis. On the other hand,
the feathers of birds and the scales of fishes belong to the
vascular layer.

•/

264. Besides these general functions of the skin, nature
has provided several other means for carrying out of the
system the superfluous parts, the most important of which
are exhalation and secretion. We have already seen (37)
that there is a general property of all animal tissues, called
endosmosis and exosmosis, by which they may be traversed
by liquids and gases. The blood vessels, especially the
capillary vessels, share this property of permeability to
liquids. Hence, while the circulation goes on, portions of
the circulating fluid, especially its watery parts, escape
through the walls of the vessels, and pass off at the
surface. This superficial loss, termed exhalation, is most
active where vessels most abound, and accordingly most
copious from the surface of the lungs. It has been esti-
mated that, under certain circumstances, the human body
loses, by exhalation, five eighths of the whole weight
of substances taken into it.

265. SECRETION is a more complicated process than ex-
halation. It is not a mere mechanical operation, but is ac-

100

OF THE SECRETIONS.

complished by means of peculiar organs, called glands ;
which elaborate peculiar juices, such as the sweat, the
tears, the milk, the saliva, the bile, the urine, &c.

266. At first glance there would seem to be nothing in
common between the organs which secrete the tears and
that which produces the bile, or between the kidneys and
the salivary glands. Still they all have the same element-
ary structure. Every gland is composed of minute vesi-
cles, or extremely thin membranous sacs, generally too
small to be discerned by the naked eye, but easily distin-
guished by the microscope. Sometimes these vesicles are

single and open sepa-
rately at the surface ;
they are then called
crypts or follicles,
but more frequently
they unite to form
Fig. 93. clusters opening into a

common canal, which itself unites with

the canals of similar clusters to form

trunks of various sizes, such as are

found in the salivary glands (Fig. 92),

in the mamma?, or in the liver, which is

merely a very large gland receiving a

large quantity of blood from the veins

of the alimentary canal. Fig. 94.

267. Sometimes the canals of the little clusters do not
unite, but open separately upon the surface of the body or
into its cavities, as in the intestinal glands or those from
which the perspiration issues (Fig. 94, g). Occasionally, the
canals themselves combine into bundles composed of a mul-
titude of parallel tubes, as we find in the kidneys.

268. The operation of the glands is one of the most ex-
traordinary and mysterious of the whole organization. By
virtue of the peculiar properties with which they are en-

OF THE SECRETIONS. 101

dowed, they select from the blood, which penetrates to their
remotest ramifications, the elements of the special humors
they are designed to elaborate. Thus the liver extracts
the elements of the bile ; the salivary glands the elements
of saliva ; the pancreas those of the pancreatic juice ;
and the sudoriferous glands those of the sweat, &c.

269. Among the humors thus formed by the different
glands, some are immediately expelled, and the body
freed from them, as the sweat, the urine, &c. ; these are
denominated excretions. Others, on the contrary, which
are properly denominated secretions, are destined either to
be used as food for the young, as the milk ; or to take part
in the different functions of the body, as the saliva, the
tears, the gastric and pancreatic juices, and the bile. The
last is the most important of all the secretions, and
hence a liver, or some analogous organ by which bile is
secreted, is found in animals of every department, whilst
most of the other glands are only found in certain classes of
animals.

270. In the vertebrates the liver is the largest of the vis-
cera. It is of a reddish brown color, and varies but little in
the different classes. In the mollusks it is no less preponde-
rant. In the gasteropods, like the snails, it envelops the in-
testine in its folds (Fig. 52) ; and in the acephala, like the
clam and oyster, it generally surrounds the stomach. In the
articulated animals it is not so compact, nor so voluminous
as in the mollusks. In insects it is represented by long
tubes variously contorted and interlaced (Fig. 51). In the
Eadiata this organ is largely developed, especially among
the echinoderms. In the star-fishes it is very large, ex-
tending into all the recesses of the arms ; and in color and
structure resembles that of the mollusks. Even in polyps
we find peculiar brown cells lining the stomach, which
probably perform functions similar to those of the liver of
higher animals,

CHAPTER TENTH.
EMBRYOLOGY.

SECTION I.

OF THE EGG.

271. THE functions of vegetative life, of which we have
treated in the preceding chapters, namely, digestion, circu-
lation, respiration and secretion, have for their end the pre-
servation of the individual. We have now to treat of the
functions that serve for the perpetuation of the species,
namely those of reproduction (200).

272. It is a law of nature that animals as well as plants
are preceded only by individuals of the same species ; and
vice versa, that none of them can produce a species differ-
ent from themselves. Reproduction in animals is almost
universally accomplished by the association of individuals of
two kinds, males and females, living commonly in pairs or
flocks, and each of them characterized by peculiarities of
structure and external appearance.

273. As this distinction prevails throughout the animal
kingdom, it is always necessary for obtaining a correct and
complete idea of a species, to bear in mind the peculiarities
of both sexes. Every one is familiar with the differences
between the cock and the hen, the lion and the lioness.

OF THE EGG. 103

Among Articulata, the differences are no less striking, the
male being often of a different shape or color, as in crabs ;
or having even more complete organs, as in many tribes of
insects, where the males have wings, while the females are
deprived of them.

274. Even higher than specific distinctions are based
upon peculiarities of the sexes ; for example, the whole
class of Mammalia is characterized by the fact that the
female is furnished with organs for nourishing her young
with a peculiar liquid, the milk, secreted by herself. Again,
the order Marsupialia, to which the opossum belongs, is dis-
tinguished by the circumstance of the female having a
pouch in which the young are received after birth.

275. That all animals are produced from eggs, (Omne
vivum ex ovo], is an old adage in Zoology, which modern
researches have fully confirmed. In tracing back the phases
of animal life, we invariably arrive at an epoch when the
incipient animal is enclosed within an egg. It is then called
an embryo, and the period passed in this condition is called
the embryonic period.

276. Before the various classes of the animal kingdom
had been attentively compared during the embryonic period,
all animals were divided into two great divisions : the ovi-
parous, comprising those which lay eggs, such as birds,
reptiles, insects, mollusks, dec., and the viviparous, which
bring forth their young alive, namely, the mammalia.
This distinction lost much of its importance when it was
shown that viviparous animals are produced from eggs, as
well as the oviparous ; only that their eggs, instead of being
laid before the development of the embryo begins, undergo
their early changes in the body of the mother. Production
from eggs should therefore be considered as a universal
characteristic of the Animal Kingdom.

277. Form of the Egg. — The general form of the egg

104

EMBRYOLOGY.

Fig. 96.

Fig. 97.

is more or less spherical. The eggs of birds have the form
of an elongated spheroid ; and this form is so constant, that
the term oval has been universally adopted to designate it.
But this is by no means the usual form of the eggs in other

animals. In most instances, on the
con trary, they are spherical, espe-
cially among the lower animals.
Fig. 95. Some have singular appendages,

as those of the skates and sharks (Fig. 95), which are shaped
like a hand-barrow, with four hooked horns at the corners.
The eggs of the hydra, or fresh
water polyps, are thickly covered
with prickles (Fig. 96). Those
of certain insects, for example the
Podurella, are furnished with fila-
ments which give them a hairy aspect (Fig. 97) ; others
are cylindrical or prismatic, and frequently the surface is
sculptured.

278. Formation of the Egg. — The egg originates within
peculiar organs, namely, the ovaries, which are glands,
ordinarily situated in the abdominal cavity. So long as they
remain in the ovary, they are very minute in size. In this
condition they are called ovarian, or primitive eggs.
They are nearly the same in all animals, and
are in fact merely little cells containing yolk-
substance (?/), including other similar cells,
namely, the germinative vesicle (g), and the
germinative dot (rf). The yolk-substance it-
self is deposited in the ovary, and afterwards
enclosed in ceils. The number of these eggs is large in
proportion as the animal stands lower in the class to which it
belongs. The ovary of a herring contains more than
25,000 eggs ; whilst that of birds contains a much smaller
number, perhaps one or two hundred.

Fig. 98.

OF THE EGG. 105

279. Ovulation. — Having attained a certain degree of
maturity, which varies in different classes, the eggs leave
the ovary. This is called ovulation. It must not be con-
founded with the laying of the eggs, which is the subsequent
expulsion of them from the abdominal cavity, either imme-
diately, or through a particular canal, the oviduct. Ovula-
tion takes place at certain seasons of the year, and never
before the animal has reached a particular age, which com-
monly coincides with its full growth. In a majority of spe-
cies, ovulation is repeated for a number of years consecu-
tively, generally in the spring, and frequently several times
a year. In others, on the contrary, it occurs but once
during life, at the period of maturity, and the animal
soon afterwards dies. Thus the butterfly dies shortly after
having laid her eggs.

280. The period of ovulation is one of no less interest to
the zoologist than to the physiologist, since the peculiar
characteristics of each species are then most clearly
marked. Ovulation is to animals what flowering is to
plants ; and indeed, few phenomena are more interesting to
the student of nature than those exhibited by animals at the
pairing season. Then their physiognomy is the most
animated, their song the most melodious, and their attire the
most brilliant. Some birds appear so different at this time,
that zoologists are always careful to indicate whether or not
a bird is represented at the breeding season. Similar differ-
ences occur also among fishes and other animals, whose
colors are then much brighter.

281. Laying. — After leaving the ovary, the eggs are
either discharged from the animal, that is, laid ; or they
continue their development within the parent animal, as is
the case in some fishes and reptiles, which for that reason
have been named ovo -viviparous animals. The eggs of the
mammalia are not only developed within the mother, but

106 EMBRYOLOGY.

become intimately united to her ; this peculiar mode of de-
velopment has received the name of gestation.

282. Eggs are sometimes laid one by one, as in birds ;
sometimes collectively and in great numbers, as in the
frogs, the fishes, and most of the invertebrates. In
some instances they are united in clusters by a
gelatinous envelop ; or are enclosed in cases or be-
tween membranous discs, forming long strings, as in
the eggs of the Pyrula (Fig. 99). The conditions

FigToi. under which the eggs of different animals are
placed, on being laid, are very different. The
eggs of birds, and of some insects, are deposited
in nests constructed for that purpose by the
parent. Other animals carry their eggs at-
tached to their bodies ; sometimes under the
tail, as in the lobsters and crabs, sometimes
hanging in large bundles on both sides of the
tail, as in the Monoculus (Fig. 100, a).

283. Some toads carry them on the back, Fig. 100.
and, what is most extraordinary, it is the male which under-
takes this office. Many mollusks, the Unio for example, have
them attached to the gills during incubation. In the polyps
they hang in clusters (Fig. 77, o), either inside or outside, at
the bottom of the cavity of the body. Some insects, such as
the gad-flies, deposit their eggs on other animals. Finally,
many abandon their eggs to the elements, taking no fur-
ther care of them after they have been laid ; such is the
case with most fishes, some insects, and many mol-
lusks. As a general rule, it may be said that animals take
the more care of their eggs and brood, as they occupy a
higher rank in their proper class.

284. The development of the embryo does not always take
place immediately after the egg is laid. A considerable
time even may elapse before it commences. Thus, the first

OF THE EGG. 107

eggs laid by the hen do not begin to develop until the whole
number which is to constitute the brood is deposited. The
eggs of the butterfly and of most insects are laid in autumn,
and remain in the same condition until the following spring.
Daring this time the principle of life in the egg is not
extinct, but is simply inactive, or in a latent state. This
tenacity of life is displayed in a still more striking man-
ner in plants. The seeds, which are equivalent to eggs,
preserve for years, and even for ages, their power to germi-
nate. Thus, wheat taken from the catacombs of Egypt
has been made to sprout and grow in some well-authenti-
cated cases.

285. A certain degree of warmth is requisite for the
hatching of eggs. Those of birds, especially, demand a uni-
form temperature, corresponding to the natural heat of the
future bird, to be constantly applied for a certain length of
time ; this is naturally supplied by the body of the parent.
In other words, incubation is necessary for their growth.
Incubation is not a purely vital phenomenon, but may be
readily imitated by artificial means. Some birds of warm
climates dispense with this task ; for example, the ostrich
often contents herself with depositing her eggs in the sand
of the desert, where they are hatched of themselves. In
like manner, the eggs of most birds may be hatched at will,
by maintaining them at the proper temperature. Before en-
tering into the details of embryonic transformations, a few
words are necessary respecting the composition of the egg.

286. Composition of the Egg. — The egg is composed
of several substances, varying in structure, as well as in
appearance. Thus, in a a new laid hen's egg (Fig. 101),
we have first a calcareous shell ; then an albuminous sub-
stance, the wldie ; within this the yolk ; and before it was
laid, there was in the midst of the latter a minute vesicle,
the germinative vesicle (Fig. 99, ^), containing a still smaller

108 EMBRYOLOGY.

one, the germinative dot (d). These different parts are

not equally important in a physio-
logical point of view. The most
conspicuous of them, namely, the
shell and the white, are not essential
parts, and therefore are often want-
ing ; while the yolk, the germinative
Fig. 101. vesicle, and the germinative dot are

found in the eggs of all animals, and out of these, and

these only, the germ is formed, in the position shown by

Fig. 101, e.

287. The vitellus or yolk (Fig. 101, y) is the most essential
part of the egg. It is a liquid of variable consistence, some-
times opaque, as in the egg of birds, sometimes transparent
and colorless, as in the eggs of some fishes and mollusks.
On examination under the microscope, it appears to be com-
posed of an accumulation of granules. The yolk is sur-
rounded by a very thin skin, the vitelline membrane (Fig.
98, v). In some insects, when the albumen is wanting, this
membrane forms the exterior covering of the egg ; in such
cases it is generally of a firm consistence, and sometimes
even horny.

288. The germinative vesicle (Fig. 98, g) is a cell of ex-
treme delicacy, situated, in the fresh egg, near the middle of
the yolk, and easily recognized by the greater transparency
of its contents when the yolk is opaque, as in the hen's egg,
or by its outline, when the yolk itself is transparent, as in the
fish. It contains one or more little spots, somewhat opaque,
appearing as small dots, the germinal dots (rf). On closer
examination these dots are themselves found to contain
smaller nucleoli.

289. The albumen, or white of the egg, (Fig. 101, a), is a
viscous substance, generally colorless, but becoming white on
coagulation. Voluminous as it is in bird's eggs, it neverthe-

DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 109

less plays but a secondary part in the history of their devel-
opment. It is not formed in the ovary, like the yolk, but is
secreted by the oviduct, and deposited around the yolk
during the passage of the egg through that canal. It con-
sists of several layers, one of which, the chalaza (c), is
twisted. On this account, the eggs of those animals in
which the oviduct is wanting are generally without the albu-
men. Like the yolk, the albumen is surrounded by a single
or double membrane, the shell membrane, which, in birds
and some reptiles and mollusks, is again protected by a cal-
careous covering, forming a true shell (s). In most cases,
however, this envelop continues membranous, particularly in
the eggs of the mollusks, most crustaceans and fishes, sala-
manders, frogs, &c. Sometimes it is horny, as in the sharks
and skates.

SECTION II.

DEVELOPMENT OF THE YOUNG WITHIN THE EGG.

290. The formation and development of the young animal
within the egg is a most mysterious phenomenon. From a
hen's egg, for example, surrounded by a shell and com-
posed, as we have seen (Fig. 101), of the albumen and the
yolk, with a little vesicle in the middle, there is produced, at
the end of a certain time, a living animal, composed in part
of totally different elements ; endowed with organs perfectly
adapted to the exercise of all the functions of animal and
vegetative life, having a pulsating heart, intestines fitted for
digestion, organs of sense for the reception of outward im-
pressions, and having, moreover, the faculty of performing
voluntary motions, and of experiencing pain and pleasure.

10

110 EMBRYOLOGY.

To learn how this takes place is certainly sufficient to excite
the curiosity of every intelligent person.

291. By opening eggs which have been subjected to incu-
bation for different periods of time, we may easily satisfy
ourselves that these changes are effected gradually. We
thus find that those which have undergone but a short
incubation exhibit only faint indications of the future ani-
mal ; while those which have been sat upon for a longer
period include an embryo chicken proportionally more de-
veloped. Modern researches have taught us that these
gradual changes, although complicated, and at first sight so
mysterious, follow laws which are uniformly the same in
each department of the Animal Kingdom.

292. The study of these changes constitutes that peculiar
branch of Physiology called EMBRYOLOGY ; and as there are
distinctions of the four great departments of the Animal
Kingdom perceptible at an early stage of embryonic
life, quite as positive as those found at maturity ; as also,
the phases of embryonic development indicate still other
grounds for natural classification, we propose to give the
outlines of Embryology, so far as it is concerned in zoologi-
cal arrangement.

293. In order to understand the successive steps of em-
bryonic development, we must bear in mind that the whole
animal body is composed of tissues, whose elements are
cells (39). These cells are much diversified in the full
grown animal ; but, at the commencement of embryonic
life, the whole embryo is composed of minute cells of nearly
the same form and consistence. These cells originate
within the yolk, and constantly undergo new changes under
the influence of life. New cells are formed, while others
disappear, or are modified so as to become blood, bones,
muscles, nerves, &c.

294. We may form some idea of this singular process, by
noticing how, in the healing of a wound, new substance

DEVELOPMENT OF THE YOUNG WITHIN THE EGG. Ill

and a new skin is supplied by the transformations of the
blood. Similar changes take place in the embryo, during
its early life ; only, instead of being limited to a part of
the body, they pervade the whole animal.

295. The series of changes commences, in most animals,
soon after the eggs are laid ; in others, the birds for
example, they are delayed till the commencement of
incubation. The yolk, which before was a mass of uni-
form appearance, now begins to present a diversified
aspect. Some portions become more opaque, and others
more transparent ; and the germinal vesicle, which was
in the midst of the yolk, is seen at the upper part of it,
where the germ is to be formed. These early changes
are accompanied, in some animals, by a rotation of the
yolk inside of the egg, as may be distinctly seen in the
eggs of some of the mollusks, especially of the snails.

296. At the same time the yolk divides itself into two
spheres, which are again regularly subdivided into two more,
and so on, till the whole yolk assumes the form of a mulberry,
each of the spheres composing the mulberry having in its inte-
rior a transparent vesicle. In many animals, however, these
divisions or fissures are only temporary, and seem to be mere-
ly a peculiar mode of transformation common to all inverte-
brate animals, and also to fishes, naked reptiles, and mam-
mals, but not yet observed in birds and the higher reptiles.*

297. In the next place, there appears upon the yolk of
the Vertebrates a disc-shaped protuberance, composed of
little cells, which has been variously designated under
the names of germinative disc, proligerous disc, blasto-
derma, germinal membrane, or simply the germ. This
disc gradually extends itself, until it embraces the whole,
or nearly the whole, of the yolk.

* In the Birds and higher reptiles we find, instead, a peculiar organ called
cicatricula, which may, nevertheless, have been formed by a similar pro-
cess before the egg was laid.

112

EMBRYOLOGY.

298. At this early epoch, namely, a few days, and, in

some animals, a
few hours after
development has
begun, the germ
Fig. 102. Fig. 103. consists of a sin-

gle layer composed of very minute cells, all of them having
the same appearance and the same form (Fig. 102, g). But
soon after, as the germ increases in thickness, several layers
may be discerned (Fig. 103), which become more and
more distinct.

299. The upper layer (s), in which are subsequently
formed the organs of animal life, namely, the nervous
system, the muscles, the skeleton, &c. (59), has received
the name of serous or nervous layer. The lower layer (in],
which gives origin to the organs of vegetative life, and
especially to the intestines, is called the mucous or vegeta-
tive layer, and is generally composed of larger cells than
those of the upper or serous layer. Finally, in the em-
bryos of vertebrated animals, there is a third layer (v),
interposed between the two others, and giving rise to the
organs of circulation and to the blood ; whence it has
been called blood layer, or vascular layer.

300. Even before this epoch, we can generally distin-
guish, from the manner in which the germ is modified, to
what department of the animal kingdom the individual is to
belong. Thus in the Articulata, the germ is divided into

segments, indicating the rings of the
body, as for example, in the embryo
of the crabs (Fig. 104). The germ
of the vertebrated animals, on the
other hand, displays a longitudinal
Fig. 104. Fig. 105. furrow, which marks the position
the future back-bone is to occupy (Fig. 105).

DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 113

301. The development of this furrow is highly impor-
tant in indicating the plan of structure of vertebrated ani-
mals in general, as will be shown by the following figures,
which represent vertical sections of the embryo at different
epochs.* At first the furrow (Fig. 106, I), is very shal-

Fig. 106.

Fig. 107.

Fig. 103.

low, and a little transparent narrow band appears under
it, called the primitive stripe (a). The walls of the
furrow consist of two raised edges formed by a swel-
ling of the germ along both sides of the primitive stripe.
Gradually, these walls grow higher, and we perceive that
their summits have a tendency to approach each other, as
seen in Fig. 107 ; at last they meet and unite completely,
so that the furrow is now changed into a closed canal (Fig.
108, Z>). This canal is soon filled with a peculiar liquid
from which the spinal marrow and brain are to be formed.
302. The primitive stripe is gradually obliterated by a
peculiar organ of a cartilaginous nature, the dorsal cord,
formed in the lower wall of the dorsal canal. This is
found in the embryos of all vertebrates, and is the represent-
ative of the back-bone. In the mean time, the margin of
the germ gradually extends farther and farther over the
yolk, so as finally to enclose it entirely, and form another
cavity in which the organs of vegetative life are to be
developed. Thus the embryo of vertebrates has two cavi-
ties, namely, a superior, very small one, for the nervous sys-
tem, and an inferior, much larger one, for the intestines.

* Only the cut edge of the embryo is supposed to be seen, whereas, if
viewed from above, it would be seen to extend over the yolk in every direc-
tion ; so that the furrow at b, of Fig. 106, would be seen as iu Fig. 105.

10*

1 14 EMBRYOLOGY.

303. In all classes of the Animal Kingdom, the embryo

rests upon the yolk, and covers it like a
cap. But the direction by which its edges
approach each other, and unite to form the
cavity of the body, is very unlike in differ-
ent animals ; and these several modes
are of high importance in classification.
Fi?. 109. Among the Vertebrates, the embryo lies
with its face or ventral surface towards the yolk (Fig. 109),
and thus the suture, or line at which the edges of the germ
unite to enclose the yolk, and which in the mammals forms
the navel, is found at the belly. Another suture is found
along the back, arising from the actual folding upwards of
the upper surface of the germ, to form the dorsal cavity.

304. The embryo in the Articulata, on the contrary, lies
with its back upon the yolk, as seen in the following figure,
which represents an embryo of Podurella ;
consequently the yolk enters the body from

the opposite direction ; and the suture,
which in the vertebrates is found on the
belly, is here found on the back. In the
Mollusks there is this peculiarity, that the
whole yolk is changed into the substance Fig. no.
of the embryo ; whilst in Vertebrates, a part of it is re-
served, till a later period, to be used as food by the embryo.
Among Radiata the germ is formed around the yolk, and
seems to surround the whole of it, from the first.

305. Among the vertebrated animals, the development of
the embryo may be best observed in the eggs of fishes.
Being transparent, they do not require to be cut open, and,
by sufficient caution, we may observe the whole series of
changes upon the same individual, and thus make sure of
the succession in which the organs appear ; whereas, if we
employ the eggs of birds, which are opaque, we are obliged
to sacrifice an egg for each observation.

DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 115

306. To illustrate these general views as to the develop-
ment of the embryo, we will briefly describe the principal
phases, as they have been observed in the White-fish of
Europe, which belongs to the salmon family. The follow-
ing magnified figures will illustrate this development, and
show the successive appearance of the different organs.

Fig. 111.

Fig. 112.

Fig. 113.

307. The egg when laid (Fig. Ill) is spherical, about
the size of a small pea, and nearly transparent. It has no
albumen, and the shell-membrane is so closely attached to
the membrane of the yolk, that they cannot be distinguished.
Oil-like globules are scattered through the mass of the yolk,
or grouped into a sort of disc, under which lies the germina-
tive vesicle. The first change in such an egg occurs a few
hours after it has been laid, when the shell-membrane
separates from the yolk-membrane, in consequence of the
absorption of a quantity of water (Fig. 112). Between the
shell-membrane (sm), and the yolk (?/), there is now a con-
siderable transparent space, which corresponds, in some
respects, to the albumen found in the eggs of birds.

308. Soon afterwards we see, in the midst of the oil-like

Fig. 114.

Fig. 115.

Fig. 110.

globules, a swelling in the shape of a transparent vesi-
cle (Fig. 113, g), composed of very delicate cells. This is
the first indication of the germ. This swelling rapidly en-
larges until it envelops a large part of the yolk, when a

116

EMBRYOLOGY.

depression is formed in it (Fig. 114). This depression
becomes by degrees a deep furrow, and soon after a second
furrow appears at right angles with the former, so that the
germ now presents four elevations (Fig. 115). The subdi-
vision goes on in this way, during the second and third
days, until the germ is divided into numerous little spheres,
giving it the appearance of a mulberry (Fig. 116). This
appearance, however, does not long continue ; at the end of
the third day, the fissures again disappear and leave no
visible traces. After this, the germ continues to extend
as an envelop around the yolk, which it at last entirely
encloses.

309. On the tenth day, the first outlines of the embryo
begin to appear, and we soon distinguish in it a depression
between two little ridges, whose edges are constantly ap-
proaching each other until they unite and form a canal (Fig.
117, ft), as has been before shown. At the same time

Fig. 117.

Ficr. 118.

Fig. 119.

an enlargement of one of the extremities is observed.
This is the rudiment of the head (Fig. 118), in which
may soon be distinguished traces of the three divisions
of the brain (Fig. 119), corresponding to the senses of
sight (/?i), hearing (e), and smell (jo).

310. Towards the thirteenth day we see, in the place af-
terwards occupied by the back-bone, a transparent, cartilag-
inous cord, composed of large cells, on which transverse
divisions are successively forming (Figs. 120, 121, c). This
is the dorsal cord, an organ which, as we have before seen,

DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 117

is common to all embryos of vertebrated animals. It
always precedes the formation of the back-bone ; and in
some fishes, as the sturgeon, this cartilaginous or embry-
onic state is permanent through life, and no true back-bone
is ever formed. Soon after, the first rudiments of the eye
appear, being a fold in the external membrane of the
germ, in which the crystalline lens (Fig. 121, #) is after-
wards formed. At the same time we see at the posterior
part of the head an elliptical vesicle, which is the rudiment
of the ear.

311. After the seventeenth day, the mucous layer divides
into two sheets, the inferior of which becomes the intestine.
The heart shows itself about the same time, under the form
of a simple cavity (Fig. 121, /?), in the midst of a mass
of cells belonging to the middle or vascular layer. As
soon as the cavity of the heart is closed in, regular motions
of contraction and expansion are perceived, and the glo-
bules of blood are seen to rise and fall in conformity with
these motions.

312. There is as yet, however, no circulation. It is not
until the thirtieth day that its first traces are manifest
in the existence of two currents, one running towards the
head, the other towards the trunk (Fig. 122), with sim-

-k,

Fisr. 120.

Fisr. 121.

Fig. 122.

ilar returning currents. At this time the liver begins
to form. Meanwhile the embryo gradually disengages itself,
at both extremities, from its adherence to the yolk ; the tail

118 EMBRYOLOGY.

becomes free, and the young animal moves it in violent
jerks.

313. The embryo, although still enclosed in the egg, now
unites all the essential conditions for the exercise of the
functions of animal life. It has a brain, an intestine,
a pulsating heart and circulating blood, and it moves
its tail spontaneously. But the forms of the organs are
not yet complete ; nor have they yet acquired the pre-
cise shape that characterizes the class, the family, the
genus and the species. The young White-fish is as yet
only a vertebrate animal in general, and except for
the fin that surrounds its body, might be taken for the
embryo of a frog.

314. Towards the close of the embryonic period, after the
fortieth day, the embryo acquires a more proper shape.
The head is more completely separated from the yolk,
the jaws protrude, and the nostrils approach nearer and
nearer to the end of the snout ; divisions are formed in
the fin which surrounds the body ; the anterior extremities,
which were indicated only by a small protuberance, assume
the shape of fins ; and finally, the openings of the gills
appear, one after the other, so that we cannot now fail to
recognize the type of fishes.

315. In this state, the young white-fish escapes from the

egg, about the sixtieth
day after it is laid (Fig.
123). But its develop-
ment is still incom-
Fig. 123. plete. The outlines are

yet too indistinct for us to recognize the genus and the
species to which the fish belongs ; at most we distinguish
its order only. The opercula or gill-covers are not
formed ; the teeth are wanting ; the fins have as yet no rays ;
the mouth is underneath, and it is some time before it as-

DEVELOPMENT OF THE YOUNG WITHIN THE* EGG. 119

sumes its final position at the most projecting point of the
head. The yolk is suspended from the belly, in the form of
a large bladder, but it daily diminishes in size, until it is
at length completely taken into the animal. The duration
of these metamorphoses varies extremely in different fishes ;
some accomplish it in the course of a few days, while in
others months are required.

315 a. In frogs and all the naked reptiles, the development is very
similar to that of fishes. It is somewhat different in the scaly rep-
tiles (snakes, lizards and turtles), which have peculiar membranes
surrounding and protecting the embryo during its growth. From one
of these envelops, the allanto'is (Fig. 125, a,) is derived their common
name of Allan to'idian Vertebrates, in opposition to the naked reptiles and
fishes, which are called Anallanto'idian.

315 6. The Allantoidian Vertebrates differ among themselves in several
essential peculiarities. Among Birds, as well as in the scaly reptiles, we
find at a certain epoch, when the embryo is already disengaging itself from
the yolk, a fold rising around the body from the upper layer of the germ,
so as to present, in a longitudinal section, two prominent walls (Fig. 124,

Fig. 124. Fig. 125.

xx). These walls, converging from all sides upwards, rise gradually
till they unite above the middle of the back (Fig. 125). When the
junction is effected, which in the hen's egg takes place in the course
of the fourth day, a cavity is formed between the back of the embryo
(Fig. 126, e) and the new membrane, whose walls are called the am-
nios. This cavity becomes filled with a peculiar liquid, the amniotic
water.

315 c. Soon after the embryo becomes enclosed in the amnios, a
shallow pouch forms from the mucous layer below the posterior ex-
tremity of the embryo, between the tail and the vitelline mass. This
pouch, at first a simple little sinus (Fig. 125, a), grows larger and larger,
till it forms an extensive sac, bending backwards and upwards, so as to

120

EMBRYOLOGY.

316. As a general fact, it should be further stated, that
the envelops which protect the egg, and also the embryo,
are the more numerous and complicated as animals be-
long to a higher class, and produce a smaller number of
eggs. This is particularly evident when contrasting the in-
numerable eggs of fishes, discharged almost without protec-
tion into the water, with the well-protected eggs of birds, and
still more with the growth of young mammals within the
body of the mother.

separate completely the two plates of the amnios (Fig. 126, a), and finally

Fig. 126.

to enclose the embryo, with the amnios, in another large sac. The tuhular
part of this sac, which is nearest the embryo, is at last transformed into
the urinary bladder. The heart (h) is already very large, with minute
arterial threads passing off from it.

315 d. The development of mammals exhibits the following peculiari-
ties. The egg is exceedingly minute, almost microscopical, although com-
posed of the same essential elements as those of the lower animals
The vitelline membrane, called chorion, in this class of animals, is
comparatively thicker (Fig. 127, v,) always soft, surrounded by peculiar

cells, being a kind of albumen.
The chorion soon grows proportion-
ally larger than the vitelline sphere
itself (Fig. 123, y), so as no longer to
invest it directly, being separated
from it by an empty space (&). The
germ is formed in the same position
Fig. 127. Fig. 128. as in the other classes of Vertebrates,

namely, at the top of the vitellus (Fig. 129) ; and here also two layers
may be distinguished, the upper or serous layer (s), and the lower or

DEVELOPMENT OF THE YOUNG WITHIN THE EGG. 121

317. But neither in fishes, nor in reptiles, nor in birds,
does the vitelline membrane, or any other envelop of the egg,
take any part in the growth of the embryo ; while on the
contrary, in the mammals, the chorion, which corresponds
to the vitelline membrane, is vivified, and finally becomes
attached to the maternal body, thus establishing a direct
connection between the young and the mother ; a connec-
tion which is again renewed in another mode, after birth,
by the process of nursing her milk.

mucous layer (m). As it gradually enlarges, the surface of the cho-
rion becomes covered
with little fringes, which,
at a later epoch, will
be attached to the mother
by means of similar
fringes arising from the
walls of the matrix, or
organ which contains the
embryo. Fig. 129. Fig. 130.

315 e. The embryo itself undergoes, within the chorion, changes similar
to those described in the birds ; its body and its organs are formed in the
same way; an amnios encloses it, and an allantois grows out of the lower
extremity of the little animal. As soon as the allantois has surrounded
the embryo, its blood vessels become more and more numerous, so as to

extend into the fringes of the chorion (Fig. 131,
pe), while, on the other hand, similar vessels
from the mother extend into the corresponding
fringes of the matrix (pm), but without directly
communicating with those of the chorion. These
two sorts of fringes soon become interwoven so
as to form an intricate organ filled with blood,
called the placenta, to which the embryo remains
p. .0. suspended until birth.

315 f. From the fact above stated, it is clear that there are three modifi-
cations of embryonic development among vertebrated animals, namely,
that of fishes and naked reptiles, that of scaly reptiles and birds, and that
of the mammals, which display a gradation of more and more complicated
adaptation. In fishes and the naked reptiles, the germ simply encloses
the yolk, and the embryo rises and grows from its upper part. In the
scaly reptiles and birds there is besides, an amnios arising from the peri-
pheric part of the embryo, and an allantois growing out of the lower cavity,
both enclosing and protecting the germ.

11

122 EMBRYOLOGY.

SECTION III.

ZOOLOGICAL IMPORTANCE OF EMBRYOLOGY.

318. As a general result of the observations which have
been made, up to this time, on the embryology of the vari-
ous classes of the Animal Kingdom, especially of the verte-
brates, it may be said, that the organs of the body are succes-
sively formed in the order of their organic importance,
the most essential being always the earliest to appear. In
consequence of this law, the organs of vegetative life, the
intestines and their appurtenances, make their appearance
subsequently to those of animal life, such as the nervous
system, the skeleton, &c. ; and these, in turn, are pre-
ceded by the more general phenomena belonging to the
animal as such.

319. Thus we have seen that, in the fish, the first changes
relate to the formation and furrowing of the germ, W7hich is
a character common to all classes of animals. It is not un-
til a subsequent period that we trace the dorsal groove,
which indicates that the forming animal will have a
double cavity, and consequently belong to the division of
the vertebrates ; an indication afterwards fully confirmed
by the successive appearance of the brain and the organs of
sense. Later still, the intestine is formed, the limbs
become evident, and the organs of respiration acquire
their definite form, thus enabling us to distinguish with
certainty the class to which the animal belongs. Finally,
after the egg is hatched, the peculiarities of the teeth,
and the shape of the extremities mark the genus and
species.

320. Hence, the embryos of different animals resem-

ITS ZOOLOGICAL IMPORTANCE. 123

ble each other more strongly in proportion as we examine
them at an earlier period. We have already stated that,
during almost the whole period of embryonic life, the young
fish and the young frog scarcely differ at all : so it is also
with the young snake compared with the embryo bird. The
embryo of the crab, again, is scarcely to be distinguished
from that of the insect ; and if we go still farther back in
the history of development, we come to a period when no
appreciable difference whatever is to be discovered between
the embryos of the various departments. The embryo of the
snail, when the germ begins to show itself, is nearly the
same as that of a fish or a crab. All that can be predicted
at this period is, that the germ which is unfolding itself
will become an animal ; the class and the group are not yet
indicated.

321. After this account of the history of the develop-
ment of the egg, the importance of Embryology to the
study of Zoology cannot be questioned. For evidently, if
the formation of the organs in the embryo takes place in an
order corresponding to their importance, this succession
must of itself furnish a criterion of their relative value
in classification. Thus, those peculiarities that first ap-
pear should be considered of higher value than those
that appear later. In this respect, the division of the Ani-
mal Kingdom into four types, the Vertebrates, the Articu-
latesx the Mollusks, and the Radiates, corresponds perfectly
with the gradations displayed by Embryology.

322. This classification, as has been already shown (61),
is founded essentially on the organs of animal life, the
nervous system and the parts belonging thereto, as found in
the perfect animal. Now, it results from the above account,
that in most animals the organs of animal life are precisely
those that are earliest formed in the embryo ; whereas those
of vegetative life, on which is founded the division into

124 EMBRYOLOGY.

classes, orders, and families, such as the heart, the respiratory
apparatus, and the jaws, are not distinctly formed until after-
wards. Therefore a classification, to be true and natural,
must accord with the succession of organs in the embryonic
development. This coincidence, while it corroborates the
anatomical principles of Cuvier's classification of the Ani-
mal Kingdom, furnishes us with a new proof that there
is a general plan displayed in every kind of development.

323. Combining these two points of view, that of Embry-
ology and that of Anatomy, the four divisions of the Animal
Kingdom may be represented by the four figures which
are to be found, at the centre of the diagram, at the be-
ginning of the volume.

324. The type of Vertebrates, having two cavities, one
above the other, the former destined to receive the nervous
system, and the latter, which is of a larger size, for the
intestines, is represented by a double crescent united at the
centre, and closing above, as well as below.

325. The type of Articulata, having but one cavity, and
growing from below upwards, (the nervous system forming
a series of ganglions, placed below the intestine,) is repre-
sented by a single crescent, with the horns directed up-
wards.

326. The type of Mollusks having also but one cavity, the
nervous system being a simple ring around the oesophagus,
with threads going off from it, is represented by a single
crescent with the horns turned down.

327. Finally, the type of Radiata, the radiating form of
which is seen even in the youngest individuals, is repre-
sented by a star.

CHAPTER ELEVENTH.

PECULIAR MODES OF REPRODUCTION.
SECTION I.

GEMMIPAROTJS AND FISSIPAKOUS REPRODUCTION.

328. WE have shown in the preceding chapter, that
ovulation, or the development of the embryo from the
egg, is common to all classes of animals, and must be
considered as the great law for the reproduction of species.
Two other modes of reproduction, applying to only a limited
number of animals, remain to be mentioned, namely, gem-
miparous reproduction, or multiplication by means of buds,
and fissiparous reproduction, or propagation by division ;
and also some still more extraordinary modifications yet in-
volved in much obscurity.

329. Reproduction ~by buds occurs among the polyps and
some of the infusoria. On the stalk, or even

on the body of the Hydra, and of many Infu-
soria (Fig. 132), there are' formed buds, like
those of plants. On close examination they
are found to contain young animals, at first
very imperfectly formed, and communicating
at the base with the parent body, from which
they derive their nourishment. By degrees the pig. 132.
animal is developed ; in most cases, the tube by which it is

11*

126

REPRODUCTION.

attached to the parent withers away, the animal is detached
and becomes independent. Others remain through life
attached to the parent stalk, and in this respect, present
a more striking analogy to the buds of plants. But in
the polyps, as in trees, budding is only an accessary mode
of reproduction, which presupposes a trunk already existing,
originally the product of ovulation.

330. Reproduction by division, or fissiparous reproduction,
is still more extraordinary ; it takes place only in polyps and
some infusoria. A cleft or fission at some part of the body
takes place, very slight at first, but constantly increasing in

depth, so as to become a deep
furrow, in the same way as
takes place in the yolk, at the
beginning of embryonic devel-
opment ; at the same time the
organs are divided and be-
come double, and thus two in-
dividuals are formed of one, so similar to each other that
it is impossible to say which is the parent and which the
offspring. The division takes place sometimes vertically,
as for example, in the Vorticella (Fig. 133) and in some

Fi?. 133.

Fig. 134.

Polyps (Fig. 134), and sometimes transversely. In some
Infusoria, the Paramecia, for instance, this division occurs
as often as three or four times in a day.

331. In consequence of the same faculty, many animals
are able to reproduce various parts of their bodies when
accidentally lost. It is well known that crabs and spi-
ders, on losing a limb, acquire a new one. The same

ALTERNATE AND EQUIVOCAL REPRODUCTION. 127

happens with the arms of the star-fishes. The tail of a
lizard is also readily reproduced. Salamanders even pos-
sess the faculty of reproducing parts of the head, including
the eye with all its complicated structure. Something simi-
lar takes place in our own bodies, when a new skin is
formed over a wound, or when a broken bone is reunited.

332. In some of the lower animals, this power of repara-
tion is carried much farther, and applies to the whole body,
so as closely to imitate fissiparous reproduction. If an
earth-worm be divided into several pieces, the injury is
soon repaired ; and if we cut in fragments a fresh-water
polyp, each one speedily becomes a perfect animal. Some-
thing like this reparative faculty is seen in the vegetable
kingdom, as well as the animal. A willow branch, planted
in a moist soil, throws out roots below and branches above ;
and thus, after a time, assumes the shape of a perfect tree.

333. These various modes of reproduction do not exclude
each other. All animals which propagate by gemmipa-
rous or fissiparous reproduction also lay eggs. Thus the
fresh-water polyps (Hydra) propagate both by eggs and by
buds. In Vorticella, according to Ehrenberg, all three
modes are found ; it is propagated by eggs, by buds,
and by division. Ovulation, however, is the mode of re-
production that most generally prevails ; the others, and
also alternate reproduction, are additional means employed
by nature to secure the perpetuation of the species.

SECTION II.

ALTERNATE AND EQUIVOCAL REPRODUCTION.

334. It is a matter of common observation, that individu-
als of the same species have the same general appear-

128 REPRODUCTION.

ance, by which their peculiar organization is indicated.
The transmission of these characteristics, from one gene-
ration to the next, is justly considered as one of the great
laws of the Animal and Vegetable Kingdoms. It is indeed
one of the points on which the definition of species is
founded.

335. But it does not follow that animals must resemble
their parents in every condition, and at every epoch of their
existence. On the contrary, as we have seen, this resem-
blance is very faint in most species, at birth, and some of
them, such as the butterfly and the frog, undergo complete
metamorphoses, before attaining their final shape. Never-
theless, we do not hesitate to refer the tadpole and the frog
to the same species ; and so with the caterpillar and the
butterfly, because we know that it is the same individual
observed in different stages of development.

336. There is also another series of cases in which the
offspring not only do not resemble the parent at birth, but
moreover remain different during their whole life, so that
their relationship is not apparent until a succeeding genera-
tion. The son resembles not the father, but the grand-
father ; and in some cases the resemblance reappears only
at the fourth or fifth generation, and even later. This sin-
gular mode of propagation has received the name of alter-
nate reproduction. The phenomena attending it have been
of late the object of numerous scientific researches, which
are the more deserving of our attention, as they furnish a
solution to several problems alike interesting in a zoological
and in a philosophical point of view.

337. Alternate reproduction was first observed among
the Salpse. These are marine mollusks, without shells, be-
longing to the family Tunicata. They are distinguished
by the curious peculiarity of being united together in
considerable numbers, the mouth (m) being free, so as to

ALTERNATE AND EQUIVOCAL REPRODUCTION.

129

form long chains which float in the sea (Fig. 135). The

Fig. 136.

individuals thus joined in floating colonies produce eggs ;
but in each individual there is generally but one egg formed,
which is developed in the body of the parent, and from
which is hatched a little mollusk (Fig. 136), which remains
solitary, and differs in many respects from the parent.
This little animal, on the other hand, does not produce
eggs, but propagates by a kind of budding which gives rise to
chains seen within the body of the parent (a), and these
again bring forth solitary individuals, &c.

338. In some parasitic worms, the alternate reproduction
is accompanied by still more extraordinary phenomena, as is
shown by the late discoveries of the Danish naturalist,
Steenstrup. It is well known that the stagnant pools in
which fresh- water shells (particularly the Lymnea and the
Paludina) are found, contain an innumerable variety of
minute animals of various kinds. Among these is a small
worm, known to naturalists under the
name of Cercaria (Fig. 137). When ex-
amined with a lens, it looks much like
a tadpole, with a long tail, a triangular
head, and a large sucker (a) in the mid-
dle of the body. Various viscera appear
within, and among others a very distinct
forked cord (c), which embraces the
sucker, and which is thought to be the
liver.

Fig. 137. 339. If we watch these worms, which

always abound in the neighborhood of the shells mentioned ,

130 REPRODUCTION.

we find them after a while attaching themselves, by means
of their sucker, to the body of the mollusks. When fixed
they soon undergo considerable alteration. The tail, which
is now useless, falls off, and the animal surrounds itself
with a mucous substance, in which it remains nearly motion-
less, like the caterpillar on its transformation into
the Pupa. If we remove the little animal from
its retreat we find it to be no longer a Cercaria,
but an intestinal worm called Distoma, having
the shape of Fig. 138, with two suckers. The
Distoma, therefore, is only a particular state of
the Cercaria, or rather the Cercaria is only the Fig. iss.
larva of the Distoma.

340. What now is the origin of the Cercaria ? The fol-
lowing are the results of the latest researches on this point.
At certain periods of the year, we find in the viscera of the
Lymnea (one of the most common fresh-water mollusks) a
quantity of little worms of an elongated form, with a well
marked head, and two posterior projections
like limbs (Fig. 139). On examining these
worms attentively under the microscope we
discover that the cavity of their body is filled
by a mass of other little worms, which a prac-
tised eye easily recognizes as young Cercaria,
Fig. 139. the tail and the other characteristic bifurcated
organ (a) within it being
distinctly visible (Fig. 140).
These little embryos increase //^W?^2^ \,
in size, distending the worm
which contains them, and Fig. 140.

which seemingly has no other office than to protect and
forward the development of the young Cercaria. It is, as
it were, their living envelop. On this account, it has been
called the nurse.

ALTERNATE AND EQUIVOCAL REPRODUCTION. 131

341. When they have reached a certain size, the young
Cercarise leave the body of the nurse, and move freely in the
abdominal cavity of the mollusks, or escape from it into the
water to fix themselves, in their turn, to the body of another
mollusk, and begin their transformations anew.

342. But this is not the end of the series. The nurses of

the Cercaria are themselves the offspring of little
worms of yet another kind. At certain seasons,
we find in the viscera of the Lymnea, worms
somewhat like the nurses of the Cercaria in
shape (Fig. 141), but rather longer, more slen-
der, and having a much more elongated stomach
(s). These worms contain, in the hinder part
of the body, little embryos (a), which are the
Fig. MI. y°ung nurses of Figures 139, 140. This gen-
eration has received the name of grand-nurses.

343. Supposing these grand-nurses to be the immediate
offspring of the Distoma (Fig. 138), as is probable, we have
thus a quadruple series of generation. Four generations
and one metamorphosis are required to evolve the perfect
animal ; in other words, the parent finds no resemblance
to himself in any of his progeny, until he arrives at the
great-grandson.

344. Among the Aphides, or plant-lice, the number of
generations is still greater. The first generation, which is
produced from eggs, soon undergoes metamorphoses, and
then gives birth to a second generation, wThich is followed
by a third and so on ; so that it is sometimes the eighth or
ninth generation before the perfect animal appears as male
and female, the sexes being then for the first time distinct,
and the male provided with wings. The female lays eggs
which are hatched the following year, to repeat the same
succession. Each generation is an additional step to-
wards the perfect state ; and as each member of the sue-

132 REPRODUCTION.

cession is an incomplete animal, we cannot better explain
their office, than by considering them analogous to the larvae
of the Cercaria, that is, as nurses.*

345. The development of the Medusse is not less instruct-
ive. According to the observations of M. Sars, a Norwegian
naturalist, the Medusa brings forth living young, which,
after having burst the covering of the egg, swim about
freely for some time in the body of the mother. When
born, these animals have no resemblance whatever to the
perfect Medusa. They are little cylindrical bodies (Fig.
142, «), much resembling infusoria, and like them covered
with fine cilia, by means of which they swim with much
activity.

346. After swimming about freely in the water for some
days, the little animal fixes itself by one extremity (Fig.
142, e). At the opposite -extremity a depression is gradu-

* There is a certain analogy between the larvae of the plant-louse (Aphis)
and the neuters of the working ants and bees. This analogy has given
rise to various speculations, and, among others, to the following theory,
which is not without interest. The end and aim of all alternate gene-
ration, it is said, is to favor the development of the species in its pro-
gress towards the perfect state. Among the plant-lice, as among all
the nurses, this end is accomplished unconsciously, by means of the
body of the nurse. Now a similar end is accomplished by the working
ants and bees, only, instead of being performed as an organic function, it is
turned into an outward activity, which makes them instinctively watch
over the new generation, and nurse and take care of it. It is no longer the
body of the nurse, but its instincts, which become the instrument of the
development. This seems to receive confirmation from the fact that the
working bees, like the nurses of the plant-lice, are barren females. The at-
tributes of their sex, in both, seem to consist only in their solicitude for the
welfare of the new generation, of which they are the natural guardians,
but not the parents. The task of bringing forth young is confided to other
individuals, to the queen among the bees, and to the female of the last
generation among the plant-lice. Thus the barrenness of the working bees,
which seems an anomaly as long as we consider them complete animals,
receives a very natural explanation so soon as we look upon them
merely as nurses.

ALTERNATE AND EQUIVOCAL REPRODUCTION.

133

ally formed, the four corners (&, f) become elongated,
and by degrees are transformed into tentacles (c). These

b chid

a

0

e f g Fig. 142. k

tentacles rapidly multiply, until the whole of the upper
margin is covered with them (g). Then transverse
wrinkles are seen on the body at regular distances, ap-
pearing first above and extending downwards. These
wrinkles, which are at first very slight, grow deeper and
deeper, and at the same time, the edge of each segment
begins to be serrated, so that the animal presents the ap-
pearance of a pine cone, surmounted by a tuft of tentacles
(h) ; whence the name of Strobila, which was originally given
to it, before it was known to be only a transient state of the
jelly-fish. The separation constantly goes on, until at last
the divisions are united by only a very slender axis, and
resemble a pile of cups placed within each other (i).
The divisions are now ready for separation ; the upper
ring first disengages itself, and then the others in succes-
sion.* Each segment (d) then continues its development by
itself, until it becomes a complete Medusa (k] ; while,
according to recent researches, the basis or stalk remains
and produces a new colony.

347. It is thus, by a series of metamorphoses, that the
little animal which, on leaving the egg, has the form of the

; These free segments have been described as peculiar animals, under
the name of Ephyra.

12

134 REPRODUCTION.

Infusoria, passes in succession through all the phases we have
described. But the remarkable point in these metamorpho-
ses is, that what was at first a single individual is thus
transformed, by tranverse division, into a number of en-
tirely different animals, which is not the case in ordinary
metamorphoses. Moreover, the upper segment does not
accompany the others in their development. Its office seems
to be accomplished so soon as the other segments begin to
be independent of it ; being intended merely to favor their
development, by securing and preparing the substances
necessary to their growth. In this respect it resembles the
nurse of the Cercaria.

348. The Polyps present phenomena no less numerous
and strange. The Campanularia has a branching, plant-
like form, with little cup-shaped cells on the ends and in the
axils of the branches, each of which contains a little animal.

These cups have not all the same organi-
zation. Those at the extremity of the
branches («), and which appear first, are
furnished with long tentacles, wherewith
they seize their food (Fig. 143). Those
in the axils of the branches, and which
appear late, are females (&), and have no
such tentacles. Inside of the latter, little
spherical bodies are found, each having sev-
143. " era! spots in the middle ; these are the eggs.
Finally, there is a third form, different from the two preced-
ing, produced by budding from the female polyp, to which it
in some sort belongs (c). It is within this third sort that the
eggs arrive, after having remained some time within the
female. Their office seems to be to complete the incu-
bation, for it is always within them that the eggs are
hatched.

349. The little animal, on becoming free, has not the

ALTERNATE AND EQUIVOCAL REPRODUCTION. 135

slightest resemblance to the adult polyp. As in the young
Medusa, the body is cylindrical, covered with
delicate cilia. After having remained free for
some time, the young polyp fixes itself in a flat-
tened form. By degrees a little swelling rises
at the centre which elongates, and at last forms
a stalk. This stalk ramifies, and we soon recog- pjg- 1444
nize in it the polyp of figure 143, with the three kinds of
buds, which we may consider as three distinct forms of the
same animal.

350. The development of the Campanularia presents, in
some respects, an analogy with what takes place in the re-
production of plants, and especially of trees. They should
be considered as groups of individuals, and not as single
individuals. The seed, which corresponds to the embryo of
the Polyp, puts forth a little stalk. This stalk soon ramifies
by gemmiparous reproduction, that is, by throwing out buds
which become branches. But ovulation, or reproduction
by means of seeds, does not take place until an advanced
period, and requires that the tree should have attained a
considerable growth. It then produces flowers with pistils
and stamens, that is, males and females, which are com-
monly united in one flower, but which in some instances
are separated, as in the hickories and elders.*

* Several plants are endowed with organs similar to the third form of
the Polyps, as we see it in the Campanularia ; for example, the liverwort
(Marchantiapolymorpha), which has at the base of the cup a little recep-
tacle, from the bottom of which little disc-like bodies are constantly form-
ing, which, when detached, send out roots, and gradually become complete
individuals. Besides that, we find in the Polyps, as in plants, the impor-
tant peculiarity, that all the individuals are united in a common trunk
which is attached to the soil ; and that all are intimately dependent on
each other, so that they perish if severed from the trunk. And if we com-
pare, in this point of view, the various species in which alternate reproduc-
tion has been observed, we find that the progress displayed in each type

136 REPRODUCTION.

SECTION III.

CONSEQUENCES OF ALTERNATE REPRODUCTION.

351. These various examples of alternate reproduction
render it evident, that this phenomenon can be no longer
considered as an anomaly in Nature ; but as the plan for
advancing those animals in which it occurs to the highest
point of perfection of which they are susceptible. More-
over, it has been noticed among all classes of invertebrated
animals ; while among the Vertebrates it is as yet unknown.
It would seem that the individual life of the lower animals
has not force enough to pass continuously, and, as it were,
with one stride, through all the phases of its development ;
but, in order to accomplish this, it must either be born in a
new form, as in the case of alternate reproduction, or un-
dergo metamorphoses, which are a sort of second birth.

352. Many analogies may be discovered between alter-
nate reproduction and metamorphosis. They are parallel
lines that lead to the same end, namely, the development of
the species. Nor is it rare to see them coexisting in the
same animal. Thus, in the Cercaria, we have seen an ani-
mal produced from a nurse afterwards transformed into a
Distoma, by undergoing a regular metamorphosis.

consists precisely in the increasing freedom of the individual in its various
forms. At first, we have all the generations united in a common trunk,
as in the lower Polyps and in plants ; then in the Medusa and in some of
the higher Polyps (the Coryne), the third generation begins to disengage
itself. Among some of the intestinal worms (the Distoma), the third gen-
eration is enclosed within its nurse, and this in its turn is contained in the
body of the grand-nurse, while the complete Distoma lives as a parasitic
worm in the body of other animals, or even swims freely about in the larva
state, as Cercaria. Finally, in the Plant-lice, all the generations, the
nurses as well as the perfect animals, are separate individuals.

CONSEQUENCES OF ALTERNATE REPRODUCTION. 137

353. In each new generation, as in each new metamor-
phosis, a real progress is made, and the form which results
is more perfect than its predecessor. The nurse that pro-
duces the Cercaria is manifestly an inferior state, just as the
chrysalis is inferior to the butterfly.

354. But there is this essential difference between the
metamorphoses of the caterpillar and alternate reproduction,
that in the former case, the same individual passes through
all the phases of development ; whereas, in the latter, the
individual disappears, and makes way for another, which
carries out what its predecessors had begun. It would give
a correct idea of this difference to suppose that the tadpole,
instead of being itself transformed into a frog, should die,
having first brought forth young frogs ; or that the chrysalis
should, in the same way, produce young butterflies. In
either case, the young would still belong to the same spe-
cies, but the cycle of development, instead of being accom-
plished in a single individual, would involve two or more
generations.

355. It follows, therefore, that the general practice of
deriving the character of a species from the sexual forms
alone, namely, the male and the female, is not always satis-
factory ; since there is a large number of animals whose
various phases are represented by distinct individuals, en-
dowed with peculiarities of their own. Thus, while in the
stag the species is represented by two individuals only, stag
and hind, the Medusa, on the other hand, is represented
under the form of three different types of animals ; the first
is free, like the Infusoria, the second is fixed on a stalk, like a
polyp, and the third again is free, consisting in its turn of
male and female. In the Distoma also, there are four sepa-
rate individuals, the grand-nurse, the nurse, the larva or
Cercaria, and the Distoma, in which the sexes are not sepa-

138 REPRODUCTION.

rate. Among the Aphides the number is much greater
still.

356. The study of alternate generation, besides making
us better acquainted with the organization of animals,
greatly simplifies our nomenclature. Thus, in future, in-
stead of enumerating the Distoma and the Cercaria, or the
Strobila, the Ephyra and the Medusa, as belonging to
different classes and families, only the name originally given
to the perfect animal will be retained, and the rest be struck
from the pages of Zoology, as representing only the transi-
tory phases of the same species.

357. Alternate generation always presupposes several
modes of reproduction, of which the primary is invariably by
ovulation. Thus, we have seen that the Polyps, the Medusa,
the Salpa, &c., produce eggs, which are generally hatched
within the mother. The subsequent generation, on the con-
trary, is produced in a different manner, as we have shown
in the preceding paragraphs ; as among the Medusse, by
transverse division ; among the Polyps and SalpaB, by
buds, &c.

358. The subsequent generations are, moreover, not to
be regarded in the same light as those which first spring
directly from eggs. In fact, they are rather phases of de-
velopment, than generations properly so called ; they are
either without sex, or females whose sex is imperfectly de-
veloped. The nurses of the Distoma, the Medusa, and the
Campanularia, are barren, and have none of the attributes
of maternity, except that of watching over the development
of species, being themselves incapable of producing young.

359. Another result of the above observations is this, that
the differences between animals which are produced by
alternate generation are less, the earlier the epoch at which
we examine them. No two animals can be more unlike,
than an adult Medusa (Fig. 31) and an adult Campanularia

CONSEQUENCES OF ALTERNATE REPRODUCTION. 139

(Fig. 143) ; they even belong to different classes of the
Animal Kingdom, the former being an Acaleph, the latter a
Polyp. On the other hand, if we compare them when first
hatched from the egg, they appear so much alike that it is
with the greatest difficulty they can be distinguished.
They are then little Infusoria, without any very distinct
shape, and moving with the greatest freedom. The larvse of
certain intestinal worms, though they belong to a different
department, have nearly the same form, at one period of
their life. Farther still, this resemblance extends to plants.
The spores of certain sea-weeds have nearly the same
appearance as the young Polyp, or the young Medusa ; and
what is yet more remarkable, they are also furnished with
cilia, and move about in a similar manner. But this is only
a transient state. Like the young Campanularia and the
young Medusa, the spore of the sea-weed is free for only a
short time ; soon it becomes fixed, and from that moment
the resemblance ceases.

360. Are we to conclude then, from this resemblance of
the different types of animals at the outset of life, that there
is no real difference between them ; or that the two King-
doms, the Animal and the Vegetable, actually blend be-
cause their germs are similar ? On the contrary, we
think nothing is better calculated to strengthen the idea of
the original separation of the various groups, as distinct and
independent types, than the study of their different phases.
In fact, a difference so wide as that between the adult
Medusa and the adult Campanularia must have existed even
in the young ; only it does not show itself in a manner to be
appreciable by our senses ; the character by which they sub-
sequently differ so much, being not yet developed. To
deny the reality of natural groups, because of these early
resemblances, would be to take the appearance for the
reality. It would be the same as saying that the frog and

140 REPRODUCTION.

the fish are one, because at one stage of embryonic life it is
impossible, with the means at our command, to distinguish
them.

36 J. The account we have above given of the develop-
ment, the metamorphoses and the alternate reproduction of
the lower animals, is sufficient to undermine the old theory
of Spontaneous Generation, which was proposed to account
for the presence of worms in the bodies of animals, for the
sudden appearance of myriads of animalcules in stagnant
water, and under other circumstances rendering their pre-
sence mysterious. We need only to recollect how the

Cercaria insinuates itself into the
skin and the viscera of mollusks
(339, 342), to understand how ad-

Q

mission may be gained to the most
inaccessible parts. Such beings

Fig. 145. Fig. 146. occur even in the eye of many

animals, especially of fishes ; they are numerous in the
eye of the common fresh-water perch of Europe. To the
naked eye they seem like little white spots (Fig. 145) ; but
when magnified they have the form of Fig. 146.

362. As to the larger intestinal worms found in other
animals, the mystery of their origin has been entirely
solved by recent researches. A single instance will illus-
trate their history. At certain periods of the year, the
Sculpins of the Baltic are infested by a particular species of
Tsenia or tape-worm, from which they are free at other
seasons. Mr. Eschricht, found, that at certain seasons, the
worms lose a great portion of the long chain of rings of
which they are composed. On a careful examination, he
found that each ring contained several hundred eggs, which,
on being freed from their envelop, floated in the water.
As these eggs are innumerable, it is not astonishing that the
Sculpins should occasionally swallow some of them with

SPONTANEOUS GENERATION. 141

their prey. The eggs, being thus introduced into the stom-
ach of the fish, find conditions favorable to their develop-
ment ; and thus the species is propagated, and at the same
time transmitted from one generation of the fish to another.
The eggs which are not swallowed are probably lost.

363. All animals swallow, in the same manner, with
their food, and in the water they drink, numerous eggs of
such parasites, any one of which, finding in the intestine of
the animal favorable conditions, is hatched. It is probable
that each animal affords the proper conditions for some par-
ticular species of worm ; and thus we may explain how it is
that most animals have parasites peculiar to themselves.

364. As respects the Infusoria, we also know that most
of them lay eggs. These eggs which are extremely minute,
(some of them are only T^-^IJ °f an inch in diameter), are
scattered everywhere in great profusion, in water, in the air,
in mist, and even in snow. Assiduous observers have not
only seen the eggs laid, but moreover, have followed their
development, and have seen the young animal forming in
the egg, then escaping from it, increasing in size, and, in its
turn, laying eggs. They have been able, in some instances,
to follow them even to the fifth and sixth generation.

365. This being the case, it is much more natural to sup-
pose that all the Infusoria are products of like germs, than
to assign to them a spontaneous origin altogether incompati-
ble with what we know of organic development. Their
rapid appearance is not at all astonishing, when we reflect
that some mushrooms attain a considerable size in a few
hours, but yet pass through all the phases of regular growth ;
and, indeed, since the knowledge of the different modes of
generation among the lower animals, no substantial difficul-
ties to the axiom " omne vivum ex ovo " (275), any longer
exist.

CHAPTER TWELFTH.

METAMORPHOSES OF ANIMALS.

366. UNDER the name of metamorphoses are included
those changes which the body of an animal undergoes after
its birth, and which modify, in various degrees, its organiza-
tion, form, and even its mode of life. Such modifications
are not peculiar to certain classes, as has been so long sup-
posed, but are common to all animals, without exception.

367. Vegetables also undergo metamorphoses, but with
this essential difference, that in vegetables the process con-
sists in an addition of new parts to the old ones. A succes-
sion of leaves, differing from those which preceded them,
comes on each season ; branches and roots are added to
the old stem, and woody layers to the trunk. In animals,
the whole body is transformed, in such a manner that all the
existing parts go to make up a new body. The chrysalis
becomes a butterfly ; the frog, after having been herbivorous
during its tadpole state, becomes carnivorous, and its stom-
ach is accommodated to a new mode of life ; at the same
time, instead of breathing by gills, it becomes an air-breath-
ing animal ; its tail and the gills disappearing, and legs be-
ing formed.

368. The nature, the duration, and the importance of
metamorphoses, and also the epoch at which they take
place, are subjected to infinite variations. The most striking
changes which naturally present themselves to the mind

METAMORPHOSES OF ANIMALS. 143

when we speak of metamorphoses, are those of insects.
Not merely is there a change of physiognomy and form, or
the possession of an organ more or less, but their whole or-
ganization is modified. The animal enters into new rela-
tions with the external world ; and at the same time, new
instincts are imparted to it. It has lived in water, and re-
spired by gills ; it is now furnished with a windpipe, and
breathes air. It passes by, with indifference, objects which
before were attractive, and its new instincts prompt it to seek
conditions which would have been most pernicious during
its former period of life. All these changes are brought
about without destroying the individuality of the animal.
The mosquito, which to-day haunts us with its shrill trum-
pet, and pierces us for our blood, is the same animal that
a few days ago lived obscure and unregarded in stagnant
water, under the guise of a little worm.

369. Every one is familiar with the metamorphoses of the
silk- worm. On escaping from the egg, the little worm
or caterpillar grows with great rapidity for twenty days,
when it ceases to feed, spins its silken cocoon, casts its
skin, and remains enclosed in its chrysalis state.* During
this period of its existence most extraordinary changes
take place. The jaws with which it masticated mulberry
leaves are exchanged for a coiled tongue ; the spinning
organs disappear ; the gullet is lengthened and more
slender; the stomach, which was nearly as long as the
body, is now contracted into a circular bag ; the intes-
tine, on the contrary, becomes elongated and tortuous,
having also one portion much smaller than the other.
The dorsal vessel is also shortened. The ganglions near
the head approach each other, and unite into a single

* In the raising of silk-worms this period is not waited for, but the ani-
mal is killed as soon as it has spun its cocoon.

144 METAMORPHOSES OF ANIMALS.

mass in the chest. Antennas and palpi are developed on
the head, and simple eyes are exchanged for compound ones.
The muscles, which before were uniformly distributed (159),
are now gathered into masses. The limbs are elongated,
and wings spring out from the thorax. More active motions
then reappear in the digestive organs, and the animal,
bursting the envelop of its chrysalis, issues in the form of
a winged moth.

370. The different external forms which an insect may
assume is well illustrated by one which is unfortunately too
well known in this country, namely, the canker-worm. Its
eggs are laid near the tips of the small branches of the
apple-tree, elm, and some other trees. They are hatched
about the time the tender leaves of these trees begin to unfold.

a b c d

Fig. 147.

The caterpillar (a) feeds on the leaves, and attains its full
growth at the end of about four weeks, being then not quite
an inch in length. It then descends to the ground, and
enters the earth to the depth of four or five inches, and
having excavated a sort of cell, is soon changed into a chry-
salis or nymph (&). At the usual time in the spring, it bursts
the skin, and appears in its perfect state, under the form
of a winged moth (d). In this species, however, only the
male has wings. The perfect insects soon pair, the female
(c) crawls up a tree and deposits her eggs, and then dies.

371. Transformations no less remarkable are observed
among the Crustacea. The metamorphoses in the family Cir-
rhipedes are especially striking. It is now known that the
barnacles (Balanus), which have been arranged among the

METAMORPHOSES OF ANIMALS.

145

mollusks are truly crustaceans ; and this result of modern
researches is confirmed in the clearest manner by the study
of their transformations. The following figures represent
the different phases of the duck-barnacle (Anatifa).

d Fig. 148. e

372. The Anatifa, like all Crustacea, is reproduced by
eggs, specimens of which, magnified ninety diameters, are
represented in figure 148, a. From these eggs little ani-
mals issue which have not the slightest resemblance to the
parent. They have an elongated form (Z>), a pair of ten-
tacles, and four legs, with which they swim freely in the
water.

373. Their freedom, however, is of but short duration.
The little animal soon attaches itself by means of its tenta-
cles, having previously become covered with a transparent
shell, through which the outlines of the body, and also a very
distinct eye, are easily distinguished (Fig. 148, c). Figure
148, d, shows the animal taken out of its shell. It is plainly
seen that the anterior portion has become considerably
enlarged. Subsequently, the shell becomes completed,
and the animal casts its skin, losing with it both its eyes
and its tentacles. On the other hand, a thick membrane
lines the interior of the shell, which pushes out and forms
astern (e), by means of which the animal fixes itself to

13

146

METAMORPHOSES OF ANIMALS.

marine bodies, after the loss of its tentacles. This stem
gradually enlarges, and the animal soon acquires a definite
shape, such as it is represented in figure 148, f, attached to
a piece of floating wood.

374. There is, consequently, not only a change of organi-
zation in the course of the metamorphoses, but also a change
of faculties and mode of life. The animal, at first free,
becomes fixed ; and its adhesion is effected by totally
different organs at different periods of life, first by means of
tentacles, which were temporary organs, and afterwards
by means of a fleshy stem designed especially for that
purpose.

375. The Radiata also furnish us with examples of vari-
ous metamorphoses, especially among the star-fishes. A
small species living on the coast of New England (Echi-
naster sanguinolentus) undergoes the following phases
(Fig. 149).

Fig. 149.

376. If the eggs are examined by the microscope, each
one is found to contain a small, pear-shaped body, which
is the embryo (e), surrounded by a transparent envelop.
On escaping from the egg, the little animal has an ob-
long form with a constriction at the base. This con-
striction becoming deeper and deeper forms a pedicle,
(p), which soon divides into three lobes. The disc also
assumes a pentagonal form, and five double series of vesi-
cles, which are the first rudiments of the rays, are seen
to form in the interior of the pentagon. At the same time,
the peduncle contracts still more, and at last is entirely
absorbed into the cavity of the body, and the animal soon
acquires its final form (m).

METAMORPHOSES OF ANIMALS.

147

377. Analogous transformations take place in the Comat-
ula. In early life
(Fig. 150) it is
fixed to the ground
by a stem, but be-
comes detached at
a certain epoch,
and then floats
freely in the sea
(Fig. 151). On
the other hand, Fi=- 151«

the Polypi seem to follow a reverse course,
many of them becoming fixed to the earth
after having been previously free.

Fig. iso. 378. The metamorphoses of mollusks,

though less striking, are not less worthy of notice. Thus,
the oyster, with which we are familiar in its adhering shell,
is free when young, like the clam (Mya) and most other
shell-fishes. Others, which are at first attached or sus-
pended to the gills of the mother, afterwards become free,
as the Unio. Some naked Gasteropods, the Acteon or the
Eolis, for example, are born with a shell, which they
part with, shortly after leaving the egg.

379. The study of metamorphosis is therefore of the ut-
most importance for understanding the real affinities of ani-
mals very different in appearance, as is readily shown by
the following instances. The butterfly and the earth-worm
seem, at the first glance, to have no relation whatever.
They differ in their organization no less than in their out-
ward appearance. But if we compare the caterpillar and
the worm, these two animals closely resemble each other.
The analogy however, is only transient ; it lasts only
during the larva state of the caterpillar, and is effaced as it
passes to the chrysalis and butterfly states. The latter be-

148 METAMORPHOSES OF ANIMALS.

comes a more and more perfect animal, whilst the worm
remains in its inferior state.

380. Similar instances are furnished by animals belong-
ing to all the types of the Animal Kingdom. Who would
think, at the first glance, that a Barnacle or an Anatifa were
more nearly allied to the crabs than to the oyster ? And,
nevertheless, we have seen (372), in tracing back the Anat-
ifa to its early stages, that it then bears a near resemblance
to a little Crustacean (Fig. 148, d). It is only when full
grown that it assumes its peculiar mollusk-like covering.

381. Among the Cuttle-fishes there are several, the
Loligo (Fig. 47) for example, which are characterized by
the form of their tentacles, the two interior being much
longer than the others, and of a different form ; whilst
in others, as the Octopus, they are all equal. But if we com-
pare the young, we find that in both animals the tentacles
are all equal, though they differ in number. The inequality
in the tentacles is the result of a further development.

382. Among the Radiata, the Pentacrinus and the Comat-
ula exemplify the same point. The two are very different
when full grown, the latter being a free-swimming star-fish
(Fig. 151), while the former is attached to the soil, like a
Polyp. But we have seen (377) that the same is the case
with Comatula in its early period ; and that in consequence
of a further metamorphosis, it becomes disengaged from its
stem, and floats freely in the water.

383. In the type of Vertebrates, the considerations drawn
from metamorphoses acquire still greater importance in re-
ference to classification. The Sturgeon and the White-fish
before mentioned (306) are two very different fishes ; yet,
taking into consideration their external form and bearing
merely, it might be questioned which of the two should
take the highest rank ; whereas, the doubt is very easily
resolved by an examination of their anatomical structure.

METAMORPHOSES OF ANIMALS.

149

The White-fish has a skeleton, and moreover, a vertebral
column composed of firm bone. The Sturgeon (Fig. 152),

Fig. 152.

on the contrary, has no bone in the vertebral column, except
the spines or apophyses of the vertebra. The middle part,
or body of the vertebra, is cartilaginous ; the mouth is
transverse, and underneath the head ; and the caudal fin
is unequally forked, while in the White-fish it is equally
forked.

384. If, however, we observe the young White-fish just
after it has issued from the egg (Fig. 123), the contrast will
be less striking. At this period the vertebrae are cartilagi-
nous, like those of the Sturgeon ; its mouth also is trans-
verse, and its tail undivided ; at that period the White-fish
and the Sturgeon are therefore much more alike. But this
similarity is only transient ; as the White-fish grows, its ver-
tebrae become ossified, and its resemblance to the Sturgeon
is comparatively slight. As the Sturgeon has no such
transformation of the vertebra, and is in some sense ar-
rested in its development, while the White-fish undergoes
subsequent transformation, we conclude that, compared with
the White-fish, it is really inferior in rank.

385. This relative inferiority and superiority strikes us
still more, when we compare with our most perfect fishes
(the Salmon, the Cod) some of those worm-like animals, so
different from ordinary fishes that they were formerly placed

among the worms. The Am-
phioxus, represented of its natu-
153. ml size (Fig. 153), not only

has no bony skeleton, but not even a head, properly

13*

150 METAMORPHOSES OF ANIMALS.

speaking. Yet the fact that it possesses a dorsal cord,
extending from one extremity of the body to the other,
proves that it belongs to the type of Vertebrates. But as
this peculiar structure is found only at a very early period
of embryonic development, in other fishes, we conclude that
the Amphioxus holds the very lowest rank in this class.

386. Nevertheless, metamorphoses will not indicate the
true measure of the perfection of animals, if limited to those
changes which take place after birth ; because there are
many animals which undergo no changes of great impor-
tance after their escape from the egg, and occupy, neverthe-
less, a high rank in the Zoological series, as for example,
Birds and many Mammals. The question now is, whether
such animals are developed according to different plans,
or whether their dissimilarity in that respect is merely appa-
rent, arising from an incorrect interpretation. To answer
this question, let us go back to the period anterior to
birth, and see if some connection may not be made out
between embryonic changes, and metamorphoses which
take place subsequently.

387. We have already shown that embryonic devel-
opment consists in a series of transformations ; the young
animal enclosed in the egg differing, at each period of its de-
velopment, from what it was in the preceding period. But
because these transformations precede birth, and are there-
fore not easily observed, does not make them the less
important. To be satisfied that these transformations are
real metamorphoses, in every respect similar to those
which follow birth, we have only to compare, on the other
hand, those changes which immediately precede birth with
those which immediately follow it, and we shall readily
perceive that the latter are simply a continuation of the
former, till all are completed.

388. Let us recur to the development of fishes for illus-

METAMORPHOSES OF ANIMALS. 151

tration. The young White-fish, as we have seen (315),
is far from having acquired its complete development,
when born. The vertical fins are not yet separate ; the
mouth has not yet its proper position ; the yolk has not
yet retreated within the cavity of the body, but hangs below
the chest in the form of a large vesicle. Much therefore
remains to be done, in order to complete its development.
But the fact of its being born does not prevent its future
evolution, which goes on without interruption.

389. Similar inferences may be drawn from the develop-
ment of the chicken. The only difference is that the young
chicken is born in a more complete state, the most impor-
tant transformations having taken place during the embry-
onic period, while those to be undergone after birth are less
considerable, though they complete the process begun in the
embryo. Thus we see it, shortly after birth, completely
changing its covering, and clothed with feathers instead of
down ; still later its crest appears, and its spurs begin to be
developed.

390. In certain Mammals, known under the name of
Marsupials (the Opossum and Kangaroo), the link between
the metamorphoses which take place before birth, and those
that occur at a later period, is especially remarkable. These
animals are brought into the world so weak and undeveloped
that they have to undergo a second gestation, in a pouch
with which the mother is furnished, and in which the young
remain, each one fixed to a teat, until they are entirely de-
veloped. Even those animals which are born nearest to the
complete state have, nevertheless, transformations to un-
dergo. Ruminants acquire their horns ; and the lion his
mane. Most mammals, at birth, are destitute of teeth, and
incapable of using their limbs ; and all are dependent on
the mother and the milk secreted by her, until the stomach
is capable of digesting other aliment.

152 METAMORPHOSES OP ANIMALS.

391. If it be thus shown that the transformations which
take place in the embryo are of the same nature and of the
same importance as those which occur afterwards, the cir-
cumstance that some precede and others succeed birth, can-
not make any radical distinction between them. Both are
processes of the life of the individual. Now, as life does not
commence at birth, but goes still farther back, it is quite clear
that the modifications which supervene during the former
period are essentially the same as the later ones ; and,
hence, that metamorphoses, far from being an exception in
the Animal Kingdom, are one of its general features.

392. We are therefore perfectly entitled to say that all
animals, without exception, undergo metamorphoses. Were
it not so, we should be at a loss to conceive why animals of
the same division present such wide differences ; and that
there should be, as in the class of Reptiles, some families
that undergo important metamorphoses, (the frogs, for ex-
ample), and others in which nothing of the kind is known,
(the Lizards and Tortoises).

393. It is only by connecting the two kinds of transforma-
tion, namely, those which take place before, and those after
birth, that we are furnished with the means of ascertaining
the relative perfection of an animal ; in other words,
these transformations become, under such circumstances, a
natural key to the gradation of types. At the same time,
they will force upon us the conviction that there is an immu-
table principle presiding over all these changes, and regu-
lating them in a peculiar manner in each animal.

394. These considerations are important, not only from
their bearing on classification, but not less so from the ap-
plication which may be made of them to the study of fossils.
If we examine attentively the fishes that have been found
in the different strata of the earth, we remark that those of
the most ancient deposits have in general preserved only the

METAMORPHOSES OF ANIMALS. 153

apophyses of their vertebrae, whilst the vertebrae themselves
are wanting. It would be the same, were the Sturgeons of
one of the American rivers to become petrified. As the
apophyses are the only bony portions of the vertebral
column, they alone would be preserved. Indeed, fossil
Sturgeons are known, which are in precisely this condition.
395. From the fact above stated, we may conclude
that the oldest fishes have not passed through all the
metamorphoses which our osseous fishes undergo, and
consequently that they are inferior to analogous species
of the present epoch, which have bony vertebras. Simi-
lar considerations apply to the fossil Crustacea and to the
fossil Echinoderms, when compared with the living ones,
and will probably be true of all classes of the Animal King-
dom, when fully studied as to their geological succession.

CHAPTER THIRTEENTH.

GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

SECTION I.

GENERAL LAWS OF DISTRIBUTION.

396. No animal, excepting man, inhabits every part of
the surface of the earth. Each great geographical or cli-
matal region is occupied by some species not found else-
where ; and each animal dwells within certain limits, beyond
which it does not range while left to its natural freedom, and
within which it always inclines to return, when removed by
accident or design. Man alone is a cosmopolite. His domain
is the whole earth. For him, and with a view to him, it was
created. His right to it is based upon his organization and
his relation to Nature, and is maintained by his intelligence
and the perfectibility of his social condition.

397. A group of animals which inhabits any particular
region, embracing all the species, both aquatic and terrestrial,
is called its FAUNA ; in the same manner as the plants of a
country are called its Flora. To be entitled to this name, it
is not necessary that every animal in the group should be
different from those inhabiting any other region ; it is suffi-
cient that there should be peculiarities in the distribution of
the families, genera, and species, and in the preponderance

GENERAL LAWS OF DISTRIBUTION. 155

of certain types over others, sufficiently prominent to impress
upon the group well-marked features. Thus, for example,
in the islands of the Pacific are found terrestrial animals,
altogether peculiar, and not found on the nearest continents.
There are numerous animals in New Holland differing from
any found on the continent of Asia, or, indeed, on any other
part of the earth. If, however, some species inhabiting both
shores of a sea which separates two terrestrial regions, are
found to be alike, we are not to conclude that those regions
have the same Fauna, any more than that the Flora of Lap-
land and England are alike, because some of the sea-weeds

o '

found on both shores are the same.

398. There is an evident relation between the fauna of
any locality and its climate ; and, on that account, the
faunas of the two hemispheres have been distributed into
three principal divisions, namely, the arctic, the temperate,
and the tropical faunas ; in the same manner as we have
arctic, temperate, and tropical floras. Hence also, ani-
mals dwelling at high elevations upon mountains, where the
temperature is much reduced, resemble the animals of
colder latitudes, rather than those of the surrounding plains.

399. In some respects, the peculiarities of the fauna of a
region depends upon its flora, at least so far as land animals
are concerned ; for herbivorous animals will exist only
where there is an adequate supply of vegetable food. But
taking the terrestrial and aquatic animals together, the distri-
bution of a fauna is less intimately dependent on climate
than that of a flora. Plants, in truth, are for the most part
terrestrial (marine plants being relatively very few), while
animals are chiefly aquatic. The ocean is the true home
of the Animal Kingdom ; and while plants, with the excep-
tion of the lichens and mosses, become dwarfed or perish
under the influence of severe cold, the sea teems with
animals of all classes, far beyond the extreme limit of
flowering plants.

156 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

400. The influence of climate, in the polar regions, acts
merely to induce a greater uniformity in the species of
animals. Thus the same animals inhabit the polar regions of
the three continents. The polar bear is the same in Europe,
Asia, and America, and so are also a great many birds.
In the temperate regions, on the contrary, the species
differ on each of the continents, but they still preserve the
same general features. The types are the same, but they
are represented by different species. In consequence of
these genera] resemblances, the first colonists of New
England erroneously applied the names of European
species to American animals. Similar differences are
observed as to regions of the same continent, within the
same parallels of latitude. The animals of Oregon and
of California are not the same as those of New England.
The difference, in certain respects, is even greater than
between the animals of New England and Europe, as the
researches of the naturalists of the United States Exploring
Expedition have proved. In like manner, the animals of
temperate Asia differ more from those of Europe than
they do from those of America.

401. Under the torrid zone, the Animal Kingdom, as well
as the Vegetable, attains its highest development. The ani-
mals of the tropics are not only different from those of the
temperate zone, but, moreover, they present the greatest va-
riety among themselves. The most gracefully proportioned
forms are found by the side of others the most odd, decked
with every combination of the most brilliant coloring. At the
same time, the contrast between the animals of different
continents is more marked ; and in many respects, the ani-
mals of the different tropical faunas differ not less among
themselves than they do from those of the temperate or
frozen zones. Thus, the fauna of Brazil is quite as differ-
ent from that of Central Africa as it is from that of the Uni-
ted States.

GENERAL LAWS OF DISTRIBUTION. 157

402. This diversity upon different continents cannot de-
pend simply on any influence of the climate of the tropics ;
if it were so, uniformity ought to be restored in proportion
as we recede from the tropics towards the antarctic tem-
perate regions. But, instead of this, the differences con-
tinue to increase ; — so much so, that no faunas are more in
contrast than those of Cape Horn, the Cape of Good Hope,
and New Holland. Hence other influences must be in ope-
ration besides those of climate; — influences of a higher
order, which are involved in a general plan, and intimately
associated with the development of life on the surface of
the earth.

403. Faunas are more or less distinctly limited, according
to the natural features of the earth's surface. Sometimes
two faunas are separated by an extensive chain of moun-
tains, like the Rocky Mountains. Again, a desert may in-
tervene, like the desert of Sahara, which separates the
fauna of Central Africa from that of the Atlas and the Moor-
ish coast, the latter of which is merely an appendage to the
fauna of Europe. But the sea effects the most complete
separation. The depths of the ocean are quite as impassa-
ble for marine species as high mountains are for terrestrial
animals. It would be quite as difficult for a fish or a mollusk
to cross from the coast of Europe to the coast of America,
as it would be for a reindeer to pass from the arctic to the
antarctic regions, across the torrid zone. Experiments of
dredging in very deep water have also taught us that the
abyss of the ocean is nearly a desert. Not only are no
materials found there for sustenance, but it is doubtful if ani-
mals could sustain the pressure of so great a column of
water, although many of them are provided with a system
of pores (260), which enables them to sustain a much greater
pressure than terrestrial animals.

404. When there is no great natural limit, the transition

14

158 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

from one fauna to another is made insensibly. Thus, in
passing from the arctic to the temperate regions of North
America, one species takes the place of another, a third
succeeds the second, and so on, until finally the fauna is
found to be an entirely new one, without its being always
possible to mark the precise limit between the two.

405. The range of species does not at all depend upon
their powers of locomotion ; if it were so, animals which
move slowly and with difficulty would have a narrow range,
whilst those which are very active would be widely diffused.
Precisely the reverse of this is actually the case. The com-
mon oyster extends at least from Cape Cod to the Carolinas ;
its range is consequently very great ; much more so than that
of some of the fleet animals, as, for instance, the Moose. It
is even probable that the very inability of the oyster to
travel, really contributes to its diffusion, inasmuch as being
once removed, it is difficult for it to return ; and more-
over, being fixed, and consequently unable to choose posi-
tions for its eggs, they must be left to the mercy of currents ;
while Fishes, by depositing their eggs in the bays and inlets
of the shore, undisturbed by currents and winds, secure
them from too wide a dispersion.

406. The nature of their food has an important bearing
upon the grouping of animals, and upon the extent of their
distribution. Carnivorous animals are generally less con-
fined in their range than herbivorous ones ; because their
food is almost everywhere to be found. The herbivora, on
the other hand, are restricted to the more limited regions
corresponding to the different zones of vegetation. The
same remark may be made with respect to Birds. Birds of
prey, like the eagle and vulture, have a much wider
range than the granivorous and gallinaceous birds. Still,
notwithstanding the facilities they have for change of place,
even the birds that wander widest recognize limits which

GENERAL LAWS OF DISTRIBUTION. 159

they do not overpass. The Condor of the Cordilleras does
not descend into the temperate regions of the United States ;
and yet it is not that he fears the cold, since he is frequently
known to ascend even above the highest summits of the
Andes, and disappears from view where the cold is most
intense. Nor can it be from lack of prey.

407. Again, the peculiar configuration of a country
sometimes determines a peculiar grouping of animals, into
what may be called local faunas. Such, for example, are
the prairies of the West, the Pampas of South America, the
Steppes of Asia, the Deserts of Africa ; — and for marine
animals, the basin of the Caspian. In all these localities,
animals are met with which exist only there, and are not
found except under those particular conditions.

408. Finally, to obtain a true picture of the zoological
distribution of animals, not the terrestrial types alone, but
the marine species must also be included. Notwithstanding
the uniform nature of the watery element, the animals which
dwell in it are not dispersed at random ; and though the
limits of the marine may be less easily defined than those of
the terrestrial fauna, still, marked differences of the animals
in the great basins are not less observable. Properly to ap-
prehend how marine animals may be distributed into local
faunas, it must be remembered that their residence is not in
the high sea, but along the coasts of continents and on sound-
ings. It is on the Banks of Newfoundland, and not in the
deep sea, that the great cod-fishery is carried on ; and it is
well known that when fishes migrate, they take care to run
along the shores. The range of marine species being there-
fore confined to the vicinity of the shores, their distribution
must be subjected to laws similar to those which regulate the
terrestrial faunas. As to the fresh-water fishes, not only do
the species vary in the different zones, but even the different
rivers of the same region have species peculiar to them, and
not found in neighboring streams.

160 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

409. A very influential cause in the distribution of aquatic
animals is the depth of the water. The Mollusks, and even
the Fishes found near the surface between high and low
water differ, in general, from those living at the depth of
twenty or thirty feet, and these again are found to be differ-
ent from those which are met with at a greater depth. Their
coloring, in particular, varies, according to the quantity of
light they receive, as has also been shown to be the case
with the marine plants.

410. It is sometimes the case that one or more ani-
mals are found upon a certain chain of mountains, and not
elsewhere ; as, for instance, the Mountain Sheep (Ovis
montana), upon the Rocky Mountains, or the Chamois and
the Ibex upon the Alps. The same is also the case on
some of the wide plains or prairies. This, however, does
not entitle such regions to be considered as having an inde-
pendent fauna, any more than a lake is to be regarded as
having a peculiar fauna, exclusive of the animals of the
surrounding country, merely because some of the spe-
cies found in the lake may not ascend the rivers emptying
into it. It is only when the whole group of animals inhabit-
ing such a region has such peculiarities as to give it a dis-
tinct character, when contrasted with animals found in sur-
rounding regions, that it is to be regarded as a separate
fauna. Such, for example, is the fauna of the great steppe
or plain of Gobi, in Asia ; and such indeed that of the chain
of the Rocky Mountains may prove to be, when the animals
inhabiting them are better known.

411. The migration' of animals might at first seem to
present a serious difficulty in determining the character
or the limits of a fauna ; but this difficulty ceases, if we
regard the country of an animal to be the place where it
makes its habitual abode. As to Birds, which of all animals
wander the farthest, it may be laid down as a rule, that they

DISTRIBUTION OF THE FAUNAS. 161

belong to the zone in which they breed. Thus, the gulls,
many of the ducks, mergansers, and divers, belong to the
boreal regions, though they pass a portion of the year with
us. On the other hand, the swallows and martins, and
many of the gallinaceous birds belong to the temperate
faunas, notwithstanding they migrate during winter to the
confines of the torrid zone. This rule does not apply to
the fishes, who annually leave their proper home, and mi-
grate to a distant region merely for the purpose of spawn-
ing. The Salmon, for example, comes down from the
North to spawn on the coasts of Maine and Nova Scotia.

412. Few of the Mammals, and these mostly of the tribe
of Rodents, make extensive migrations. Among the most
remarkable of these are the Kamtschatka rats. In Spring
they direct their course westward, in immense troops ; and
after a very long journey, return again in Autumn to their
quarters, where their approach is anxiously awaited by the
hunters, on account of the fine furs to be obtained from the
numerous carnivora which always follow in their train.
The migrations of the Lemmings are marked by the devas-
tations they commit along their course, as they come down
from the borders of the Frozen Ocean to the valleys of
Lapland and Norway ; but their migrations are not period-
ical.

SECTION II.

DISTRIBUTION OF THE FAUNAS.

413. We have stated that all the faunas of the globe
may be divided into three departments, corresponding to as
many great climatal divisions, namely, the glacial or arctic,
the temperate and the tropical faunas. These three divisions

14*

162 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

appertain to both hemispheres, as we recede from the equa-
tor towards the north or south poles. It will hereafter be
shown that the tropical and temperate faunas may be again
divided into several zoological provinces, depending on
longitude or on the peculiar configuration of the continents.

414. No continent is better calculated to give a correct
idea of distribution into faunas, as determined by climate,
than the continent of America ; extending as it does across
both hemispheres, and embracing all latitudes, so that all
climates are represented upon it, as shown by the chart on
the following page.

415. Let a traveller embark at Iceland, which is situated
on the borders of the polar circle, with a view to observe,
in a zoological aspect, the principal points along the eastern
shore of America. The result of his observation will be
very much as follows. Along the coast of Greenland and
Iceland, and also along Baffin's Bay, he will meet with an
unvaried fauna composed of the same animals, which are
also for the most part identical with those of the arctic
shores of Europe. It will be nearly the same along the
Labrador coast.

416. As he approaches Newfoundland, he will see the
landscape, and with it the fauna, assuming a somewhat
more varied aspect. To the wide and naked or turfy
plains of the boreal regions succeed forests, in which he
will find various animals which dwell only in forests. Here
the temperate fauna commences. Still the number of spe-
cies is not yet very considerable ; but as he advances
southwardly, along the coasts of Nova Scotia and New
England, he finds these species gradually increasing, while
those of the cold regions diminish, and at length entirely
disappear, some few accidental or periodical visitors excepted,
who wander during winter, as far south as the Carolinas.

417. But it is after having passed the boundaries of the
United States, among the Antilles, and more especially on

i

:::::::t:::v:::;:. :;::::::: .::.•::::;: ::.::::::::::::::::;::

iiJp||pK[|ili|is|ij|||ii!|:ii||

FAUNAS.

I. North Glacial or Arctic.

II. Northern Temperate.

III. Northern Warm.

IV. Tropical.

V. Southern Warm.
VI. Southern Temperate.

164 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

the southern continent, along the shores of the Orinoco and
the Amazon, that our traveller will be forcibly struck with
the astonishing variety of the animals which people the
forests, the prairies, the rivers, and the sea-shores, most of
which he will also find to be different from those of the
northern continent. By this extraordinary richness of new
forms, he will become sensible that he is now in the domain
of the tropical fauna.

418. Let him still travel on beyond the equator towards
the tropic of Capricorn, and he will again find the scene
change as he enters the regions where the sun casts his rays
more obliquely, and where the contrast of the seasons is
more marked. The vegetation will be less luxuriant ; the
palms will have disappeared to make place for other trees ;
the animals will be less varied, and the whole picture will
recall to him, in some measure, what he witnessed in the
United States. He will again find himself in the temperate
regions, and this he will trace on, till he arrives at the ex-
tremity of the continent, the fauna and the flora becoming
more and more impoverished as he approaches Cape Horn.

419. Finally, we know that there is a continent around
the South Pole. Although we have as yet but very imper-
fect notions respecting the animals of this inhospitable
clime, still the few which have already been observed
there, all present a close analogy to those of the arctic re-
gion. It is another glacial fauna, namely, the antarctic.
Having thus sketched the general distribution of the fauna,
it remains to point out the principal features of each of
them.

420. I. ARCTIC FAUNA. — The predominant feature of
the Arctic Fauna is its uniformity. The species are few in
number ; but, on the other hand, the number of individuals
is immense. We need only refer to the clouds of birds
which hover upon the islands and shores of the North ; the

DISTRIBUTION OF THE FAUNAS. 165

shoals of fishes, the salmon among others, which throng the
coasts of Greenland, Iceland, and Hudson's Bay. The
same uniformity appears in the form and color of the animals.
There is not a single bird of brilliant plumage, and not a
fish with varied hues. Their forms are regular, and their
tints as dusky as the northern heavens. The most conspicu-
ous animals are the white-bear, the moose, the reindeer,
the musk-ox, the white-fox, the polar-hare, the lemming,
and various Seals ; but the most important are the Whales,
which, it is to be remarked, rank lowest of all the Mam-
mals. Among the Birds, may be enumerated some sea-
eagles and a few Waders, with an immense number
of other aquatic species, such as gulls, cormorants, di-
vers, petrels, ducks, geese, &c., all belonging to the
lowest order of Birds. Reptiles are altogether wanting.
The Articulata are represented by numerous marine worms,
and by minute crustaceans of the orders Isopoda and Am-
phipoda. Insects are rare, and of inferior types. Of the
type of Mollusks, there are Acephala, particularly Tunicata,
fewer Gasteropods, and very few Cephalopods. Among the
Radiata are a great number of jelly-fishes, particularly the
Beroe ; and to conclude with the Echinoderms, there are
several star-fishes and Echini, but few Holothurise. The
class of Polypi is very scantily represented, and those pro-
ducing stony corals are entirely wanting.

421. This assemblage of animals is evidently inferior to
that of other faunas, especially to those of the tropics. Not
that there is a deficiency of animal life ; for if the spe-
cies are less numerous, there is a compensation in the
multitude of individuals, and also in this other very sig-
nificant fact, that the largest of all animals, the whales,
belong to this fauna.

422. It has already been said (400) that the arctic fauna
of the three continents is the same ; its southern limit, how-

166 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

ever, is not a regular line. It does not correspond precisely
with the polar circle, but rather to the isothermal zero, that
is, the line where the average temperature of the year is
at 32° of Fahrenheit. The course of this line presents
numerous undulations. In general, it may be said to coin-
cide with the appearance of trees, so that it passes
where forest vegetation succeeds the vast arid plains, the
barrens of North America, or the tundras of the Samoyedes.
The uniformity of these plains involves a corresponding
uniformity of plants and animals. On the North American
continent it extends much farther southward on the east-
ern shore, than on the western. From the peninsula of
Alashka it bends northwards towards the Mackenzie, then
descends again towards the Bear Lake, and comes down
to near the northern shore of Newfoundland.

423. II. TEMPERATE FAUNAS. — The faunas of the tem-
perate regions of the northern hemisphere are much more
varied than that of the arctic zone. Instead of consisting
mainly of aquatic tribes, we have a considerable number
of terrestrial animals of graceful form, animated appearance,
and varied colors, though less brilliant than those found in
tropical regions. Those parts of the country covered with
forests especially swarm with insects, worms, terrestrial and
fluviatile mollusks, which become the food of still other
animals.

424. Still, the climate is not sufficiently warm over the
whole extent of this zone to allow the trees to retain their
foliage throughout the year. At its northern margin the
leaves, excepting those of the pines and spruces, fall, on
the approach of the cold season, and vegetation is ar-
rested for a longer or shorter period. Insects retire,
and the animals which live upon them no longer find
nourishment, and are obliged to migrate to warmer re-
gions, on the borders of the tropics, where, on the ever-
verdant vegetation, they find the means of subsistence.

DISTRIBUTION OF THE FAUNAS. 167

425. Some of the herbivorous Mammals, the Bats, and
the reptiles which feed on insects, pass the winter in a state
of torpor, from which they awake in spring. Others retire
into dens, and live on the provisions they have stored up
during the warm season. The Carnivora, the Ruminants,
and the most active portion of the Rodents, are the only
animals that do not change either their abode or their
habits. The fauna of the temperate zone thus presents an
ever-changing picture, which may be considered as one of
its most important features, since these changes recur with
equal constancy in the Old and the New World.

426. Taking the contrast of the vegetation, as a basis,
and the consequent changes of habit imposed upon the
denizens of the forests, the temperate fauna has been
divided into two regions ; a northern one, where the
trees, except the pines, drop their leaves in winter, and
a southern one, where they are evergreen. Now, as
the limit of the former, that of the deciduous trees, coin-
cides, in general, with the limit of the pines, it may be
said that the cold region of the temperate fauna extends as
far as the pines. In the United States this coincidence is
not so marked as in other regions, inasmuch as the pines
extend into Florida, while they do not prevail in the West-
ern States ; but we may reckon as belonging to the southern
portion of the temperate region, that part of the country south
of the latitude where the Palmetto or Cabbage-tree (Cha-
mczrops) commences, namely, all the States to the south of
North Carolina ; while the States to the north of this limit
belong to the northern portion of the temperate region.

427. This division into two zones is supported by obser-
vations made on the maritime faunas of the Atlantic coast.
The line of separation between them, however, being influ-
enced by the Gulf Stream, is considerably farther to the
north; — namely, at Cape Cod. It has been ascertained
that of one hundred and ninety-seven Mollusks inhabiting the

168 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

coast of New England, fifty do not pass to the north of Cape
Cod, and eighty-three do not pass to the south of it ; only
sixty-four being common to both sides of the Cape. A
similar limitation of the range of Fishes has been noticed
by Dr. Storer ; and Dr. Holbrook has found the Fishes of
South Carolina to be different from those of Florida and the
West Indies. In Europe, the northern part of the temperate
region extends to the Pyrennees and the Alps ; and its
southern portion consists of the basin of the Mediterranean,
together with the northern part of Africa, as far as the
desert of Sahara.

428. A peculiar characteristic of the faunas of the tem-
perate regions in the northern hemisphere, when contrasted
with those of the southern, is the great similarity of the
prevailing types on both continents. Notwithstanding the
immense extent of country embraced, the same stamp
is everywhere exhibited. Generally, the same families,
frequently the same genera, represented by different spe-
cies, are found. There are even a few species of terres-
trial animals regarded as identical on the continents of
Europe and America ; but their supposed number is con-
stantly diminished, as more accurate observations are made.
The predominant types among the mammals are the bison,
deer, ox, horse, hog, numerous rodents, especially squirrels,
and hares, nearly all the insectivora, weasels, martens,
wolves, foxes, wild cats, &c. On the other hand, there are
no Edentata and no Quadrumana, with the exception of
some monkeys on the two slopes of the Atlas. Among
Birds, there is a multitude of climbers, passerine, gallina-
ceous, and many rapacious birds. Of Reptiles, there
are lizards and tortoises of small or medium size, ser-
pents, and many batrachians, but no crocodiles. Of Fishes,
there is the trout family, the cyprinoids, the sturgeons, the
pikes, the cod, and especially the great family of Herrings
and Scomberoids, to which latter belong the mackerel and

DISTRIBUTION OF THE FAUNAS. 169

the tunny. All classes of the Mollusks are represented ;
though the cephalopods are less numerous than in the torrid
zone. There is an infinite number of Articulata of every
type, as well as numerous Polyps, though the corals proper
do not yet appear abundantly.

429. On each of the two continents of Europe and Amer-
ica, there is a certain number of species which extend from
one extreme of the temperate zone to the other. Such, for
example, are the deer, the bison, the cougar, the flying-squir-
rel, numerous birds of prey, several tortoises, and the rattle-
snake, in America. In Europe, the brown bear, wolf,
swallow, and many birds of prey. Some species have a
still wider range, like the ermine, which is found from
Bhering's Straits to the Himalaya Mountains, that is to say,
from the coldest regions of the arctic zone, to the southern
confines of the temperate zone. It is the same with the
muskrat, which is found from the mouth of Mackenzie's
River to Florida. The field-mouse has an equal range in
Europe. Other species, on the contrary, are limited to one
region. The Canadian elk is confined to the northern por-
tion ; and, on the other hand, the prairie wolf, the fox-
squirrel, the Bassaris and numerous birds, never leave the
southern portion.*

430. In America, as in the Old World, the temperate

* The types which are peculiar to temperate America, and are not found
in Europe, are the Opossum, several genera of Insectivora, among them
the shrew-mole (Scalops aquaticus), and the star-nose mole (Condylura
cristata), which replaces the Mygale of the Old World ; several genera
of rodents, especially the muskrat. Among the types characteristic of
America must also be reckoned the snapping-turtle among the tortoises ;
the Menobranchus and Menopoma, among the Salamanders ; the Gar-
pike and Amia among the fishes ; and finally among the Crustacea, the
Limulus. Among the types which are wanting in temperate America, and
which are found in Europe, may be cited the horse, the wild boar, and the
true mouse. All the species of domestic mice which live in America, have
been brought from the Old World.

15

170 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

fauna is further subdivided into several districts, which may
be regarded as so many zoological provinces, in each of
which there is a certain number of animals differing from
those in the others, though very closely allied. Temperate
America presents us with a striking example in this respect.
We have, on the one hand :

1st. The fauna of the United States properly so called,
on this side of the Rocky Mountains.

2d. The fauna of Oregon and California, beyond those
mountains.

Though there are some animals which traverse the chain
of the Rocky Mountains, and are found in the prairies of
the Missouri as well as on the banks of the Columbia, as,
for example, the Rocky Mountain deer, (Antilope furci-
fer), yet if we regard the whole assemblage of animals,
they are found to differ entirely. Thus, the rodents, part
of the ruminants, the insects, and all the mollusks, belong
to distinct species.

431. The faunas or zoological provinces of the Old World
which correspond to these are :

1st. The fauna of Europe, which is very closely related
to that of the United States proper.

2d. The fauna of Siberia, separated from the fauna of
Europe by the Ural Mountains.

3d. The fauna of the great Asiatic table-land, which, from
what is as yet known of it, appears to be quite distinct.

4th. The fauna of China and Japan, which is analogous
to that of Europe in the Birds, and to that of the United
States in the Reptiles — as it is also in the flora.

Lastly, it is in the temperate zone of the northern hemi-
sphere, that we meet with the most striking examples of
those local faunas which have been mentioned above.
Such, for example, is the fauna of the Caspian Sea, of the
steppes of Tartary, and of the Western prairies.

DISTRIBUTION OF THE FAUNAS. 171

432. The faunas of the southern temperate regions differ
from those of the tropics as much as the northern temperate
faunas do ; and, like them also, may be distinguished into
two provinces, the colder of which embraces Patagonia.
But besides differing from the tropical faunas, they are also
quite dissimilar to each other on the different continents.
Instead of that general resemblance, that family likeness
which we have noticed between all the faunas of the tem-
perate zone of the northern hemisphere, we find here the
most complete contrasts. Each of the three continental
peninsulas which jut out southerly into the ocean represents,
in some sense, a separate world. The animals of South
America, beyond the tropic of Capricorn, are in all respects
different from those at the southern extremity of Africa.
The hyenas, wild-boars, and rhinoceroses of the Cape of
Good Hope, have no analogues on the American continent ;
and the difference is equally great between the birds, rep-
tiles and fishes, insects and mollusks. Among the most
characteristic animals of the southern extremity of America
are peculiar species of seals, and especially, among aquatic
birds, the penguins.

433. New Holland, with its marsupial mammals, with
which are associated insects and mollusks no less singular,
furnishes a fauna still more peculiar, and which does not
approach those of any of the adjacent countries. In the
seas of that continent, where every thing is so strange, we
find the curious shark, with paved teeth and spines on the
back (Cestracion Philippii}, the only living representative of
a family so numerous in former zoological ages. But a most
remarkable feature of this fauna is, that the same types
prevail over the whole continent, in its temperate as well as
its tropical portions, the species only being different at dif-
ferent localities,

-

172 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

434. TROPICAL FAUNAS. — The tropical faunas are dis-
tinguished, on all the continents, by the immense variety of
animals which they comprise, not less than by the brilliancy
of their coverings. All the principal types of animals are
represented, and all contain numerous genera and species.
We need only refer to the tribe of humming-birds, which
numbers not less than 300 species. But what is very im-
portant is, that here are concentrated the most perfect,
and also the oddest types of all the classes of the Animal
Kingdom. The tropical region is the only one occupied by
the Quadrumana, the herbivorous bats, the great pachyder-
mata, such as the elephant, the hippopotamus, and the tapir,
and the whole family of Edentata. Here also are found the
largest of the cat tribe, the lion and tiger. Among the
Birds we may mention the parrots and toucans, as essen-
tially tropical ; among the Reptiles, the largest crocodiles,
and gigantic tortoises ; and finally, among the articu-
lated animals, an immense variety of the most beautiful
insects. The marine animals, as a whole, are equally
superior to those of other regions ; the seas teem with
crustaceans and numerous cephalopods, together with an
infinite variety of gasteropods and acephala. The Echi-
noderms there attain a magnitude and variety elsewhere
unknown ; and lastly, the Polyps there display an activity
of which the other zones present no example. Whole
groups of islands are covered with coral reefs formed by
those little animals.

435. The variety of the tropical fauna is further enriched
by the circumstance that each continent furnishes new and
peculiar forms. Sometimes whole types are limited to one
continent, as the sloth, the toucans, and the humming-birds to
America, the giraffe and hippopotamus to Africa ; and again,
animals of the same group have different characteristics, ac-

DISTRIBUTION OF THE FAUNAS. 173

cording as they are found on different continents. Thus,
the monkeys of America, have flat and widely separated
nostrils, thirty-six teeth, and generally a long, prehensile
tail. The monkeys of the old world, on the contrary,
have nostrils close together, only thirty-two teeth, and not
one of them has a prehensile tail.

436. But these differences, however important they may
appear at first glance, are subordinate to more important
characters, which establish a certain general affinity between
all the faunas of the tropics. Such, for example, is the fact
that the quadrumana are limited, on all the continents, to
the warmest regions ; and never, or but rarely, penetrate into
the temperate zone. This distribution is a natural conse-
quence of the distribution of the palms ; for as these trees,
which constitute the ruling feature of the flora of the trop-
ics, furnish, to a great extent, the food of the monkeys on
the two continents, we have only to trace the limits of the
extent of the palms, to have a pretty accurate indication of
the tropical faunas on all three continents.

437. Several well-marked faunas may be distinguished
in the tropical part of the American continent, namely :

1. The fauna of Brazil, characterized by its gigantic
reptiles, its monkeys, its Edentata, its tapir, its humming-
birds, and its astonishing variety of insects.

2. The fauna of the western slope of the Andes, com-
prising Chili and Peru ; and distinguished by its Llamas,
vicunas, and birds, which differ from those of the basin of the
Amazon, as also do the insects and mollusks.

3. The fauna of the Antilles and the Gulf of Mex-
ico. This is especially characterized by its marine ani-
mals, among which the Manatee is particularly remarkable ;
an infinite variety of singular fishes, embracing a large
number of Plectognaths ; also Mollusks, and Radiata of

15*

174 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

peculiar species. It is in this zone that the Pentacrinus
caput-medusce. is found, the only representative, in the
existing creation, of a family so numerous in ancient
epochs, the Crinoidea with a jointed stem.

The limits of the fauna of Central America cannot yet
be well defined from want of sufficient knowledge of the
animals which inhabit those regions.

438. The tropical zone of Africa is distinguished by a
striking uniformity in the distribution of the animals, which
corresponds to the uniformity of the structure and contour
of that continent. Its most characteristic species are spread
over the whole extent of the tropics : thus, the giraffe is met
with from Upper Egypt to the Cape of Good Hope. The
hippopotamus is found at the same time in the Nile, the
Niger, and Orange River. This wide range is the more
significant as it also relates to herbivorous animals, and thus
supposes conditions of vegetation very similar, over wide
countries. Some forms are nevertheless circumscribed
within narrow districts ; and there are marked differences
between the animals of the eastern and western shores.
Among the remarkable species of the African torrid region
are the baboons, the African elephant, the crocodile of the
Nile, a vast number of Antelopes, and especially two spe-
cies of Ourang-outang, the Chimpanzee and the Engeena,
a large and remarkable animal, recently described by
Drs. Savage and Wyman. The fishes of the Nile have a
tropical character, as well as the animals of Arabia, which
are more allied to those of Africa than to those of Asia.

439. The tropical fauna of Asia, comprising the two pe-
ninsulas of India and the isles of Sunda, is not less marked.
It is the country of the gibbons, the red ourang, the royal
tiger, the gavial, and a multitude of peculiar birds. Among
the fishes, the family of Chetodons is most numerously
represented. Here also are found those curious spiny

CONCLUSIONS. 175

fishes, whose intricate gills suggested the name Labyrinth-
ici, by which they are known. Fishes with tufted gills are
more numerous here than in other seas. The insects and
mollusks are no less strongly characterized. Among others
is the nautilus, the only living representative of the great
family of large, chambered-shells which prevailed so exten-
sively over other types, in former geological ages.

440. The large island of Madagascar has its peculiar
fauna, characterized by its makis and its curious rodents.
It is also the habitat of the Aya-aya. Polynesia, exclusive of
New Holland, furnishes a number of very curious animals,
which are not found on the Asiatic continent. Such are the
herbivorous bats, and the Galeopithecus or flying Maki.

SECTION III.

CONCLUSIONS.

441. From the survey we have thus made of the distribu-
tion of the Animal Kingdom, it follows :

1st. Each grand division of the globe has animals which
are either wholly or for the most part peculiar to it. These
groups of animals constitute the faunas of different regions.

2d. The diversity of faunas is not in proportion to the
distance which separates them. Very similar faunas are
found at great distances apart ; as, for example, the fauna
of Europe and that of the United States, which yet are
separated by a wide ocean. Others, on the contrary, differ
considerably, though at comparatively short distances ; as
the fauna of the East Indies and the Sunda Islands, and that
of New Holland ; or the fauna of Labrador and that of
New England.

3d. There is a direct relation between the richness of a

176 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

fauna and the climate. The tropical faunas contain a much
larger number of more perfect animals than those of the
temperate and polar regions.

4th. There is a no less striking relation between the fauna
and flora, the limit of the former being oftentimes deter-
mined, so far as terrestrial animals are concerned, by the
extent of the latter.

442. Animals are endowed with instincts and faculties
corresponding to the physical character of the countries
they inhabit, and which would be of no service to them
under other circumstances. The monkey, which is a
frugivorous animal, is organized for living on the trees
from which he obtains his food. The reindeer, on the
contrary, whose food consists of lichens, lives in cold
regions. The latter would be quite out of place in the
torrid zone, and the monkey would perish with hunger in
the polar regions. Animals which store up provisions are
all peculiar to temperate or cold climates. Their instincts
would be uncalled for in tropical regions, where the vege-
tation presents the herbivora with an abundant supply of
food at all times.

443. However intimately allied the climate of a country
may be to the peculiar character of its fauna, we are not to
conclude that the one is the consequence of the other.
The differences which are observed between the animals of
different faunas are no more to be ascribed to the influences
of climate, than their organization is to the influence of the
physical forces of nature. If it were so, we should necessa-
rily find all animals precisely similar, when placed under
the same circumstances. We shall find, by the study of the
different groups in detail, that certain species, though very
nearly alike, are nevertheless distinct in two different faunas.
Between the animals of the temperate zone of Europe, and
those of the United States, there is similarity, but not iden-

CONCLUSIONS. 177

tity ; and the particulars in which they differ, though appa-
rently trifling, are yet perfectly constant.

444. Fully to appreciate the value of these differences, it
is often requisite to know all the species of a genus
or of a family. It is not uncommon to find, upon such an
examination, that there is often the closest resemblance be-
tween species that dwell far apart from each other, while
species of the same genus, that live side by side, are widely
different. This may be illustrated by a single example.
The Menopoma, Siren, Amphiuma, Axolotl, and the Meno-
branchus, are Batrachians which inhabit the rivers and lakes
of the United States and Mexico. They are very similar in
external form, yet differ in some of them having external
gills at the sides of the head, while others have them not; and
also in having either two or four legs. Hence we might
be tempted to refer them to different types, did we not know
intermediate animals, completing the series, namely, the
Proteus and Megalobatrachus. Now the former exists only
in the lakes of Austria, and the latter in Japan. The con-
nection in this case is consequently established by means
of species which inhabit distant continents.

445. Neither the distribution of animals therefore, any more
than their organization, can be the effect of external influ-
ences. We must, on the contrary, see in it the realization
of a plan wisely designed, the work of a Supreme Intelli-
gence who created, at the beginning, each species of animal
at the place, and for the place, which it inhabits. To each
species has been assigned a limit which it has no disposition
to overpass so long as it remains in a wild state. Only
those animals which have been subjected to the yoke of
man, or whose subsistence is dependent on man's social
habits, are exceptions to this rule.

446. As the human race has extended over the surface of
the earth, man has more or less modified the animal popu-

178 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

lation of different regions, either by exterminating certain
species, or by introducing others with which he desires to be
more intimately associated, — the domestic animals. Thus,
the dog is found wherever we know of the presence of man.
The horse, originally from Asia, was introduced into Amer-
ica by the Spaniards ; where it has thrived so well, that
it is found wild, in innumerable herds, over the Pampas of
South America, and the prairies of the West. In like
manner the domestic ox became wild in South America.
Many less welcome animals have followed man in his peri-
grinations ; as, for example, the rat and the mouse, as well
as a multitude of insects, such as the house-fly, the cock-
roach, and others which are attached to certain species of
plants, as the white-butterfly, the Hessian-fly, &c. The
honey-bee also has been imported from Europe.

447. Among the species which have disappeared, under
the influence of man, we may mention the Dodo, a pecu-
liar species of bird which once inhabited the Mauritius,
some remains of which are preserved in the British and
Ashmolean Museums ; a large cetacean of the north (Rytina
Stelleri), which formerly inhabited the coasts of Behring's
Straits, and which has not been seen since 1768. According
to all appearances, we must also reckon among these the
great stag, the skeleton and horns of which have been found
buried in the peat-bogs of Ireland. There are also many
species of animals whose numbers are daily diminishing, and
whose extinction may be foreseen ; as the Canada deer
(Wapiti] , the Ibex of the Alps, the Lammergeyer, the
bison, the beaver, the wild-turkey, &c.

448. Other causes may also contribute towards dispersing
animals beyond their natural limits. Thus the sea-weeds
are carried about by marine currents, and are frequently
met with far from shore, thronged with little crustaceans,
which are in this manner transported to great distances from

CONCLUSIONS. 179

the place of their birth. The drift-wood which the Gulf
stream floats from the Gulf of Mexico even to the western
shores of Europe, is frequently perforated by the larvae of
insects, and may probably serve as depositories for the eggs
of fishes, Crustacea and mollusks. It is possible also that
aquatic birds may contribute in some measure to the diffu-
sion of some species of fishes and mollusks, either by the
eggs becoming attached to their feet, or by means of those
which they evacuate undigested, after having transported
them to considerable distances. Still, all these circum-
stances exercise but a very feeble influence upon the distri-
bution of species in general, and each country, none the less,
preserves its peculiar physiognomy, so far as its animals are
concerned.

449. There is only one way to account for the distribu-
tion of animals as we find them, namely, to suppose that
they are autochthonal, that is to say, that they originated
like plants, on the soil where they are found. In order to
explain the particular distribution of many animals, we are
even led to admit that they must have been created at
several points of the same zone, as we must infer from the
distribution of aquatic animals, especially that of Fishes.
If we examine the fishes of the different rivers of the United
States, peculiar species will be found in each basin, associated
with others which are common to several basins. Thus, the
Delaware River contains species not found in the Hudson.
But, on the other hand, the pickerel is found in both.
Now if all animals originated at one point, and from a single
stock, the pickerel must have passed from the Delaware to
the Hudson, or vice versa, which it could only have been
done by passing along the sea-shore, or by leaping over large
spaces of terra firma ; that is to say, in both cases it would
be necessary to do violence to its organization. Now such

180 GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

a supposition is in direct opposition to the immutability of
the laws of Nature.

450. We shall hereafter see that the same laws of distri-
bution are not limited to the actual creation only, but that
they have also ruled the creations of former geological
epochs, and that the fossil species have lived and died, most
of them, in the spot where their remains are found.

451. Even Man, although a cosmopolite, is subject, in a
certain sense, to this law of limitation. While he is every-
where the one identical species, yet several races, marked
by certain peculiarities of features, are recognized ; such as
the Caucasian, Mongolian, and African races, of which we
are hereafter to speak. And it is not a little remarkable,
that the abiding places of these several races correspond
very nearly, with some of the great zoological regions.
Thus we have a northern race, comprising the Samoyedes
in Asia, the Laplanders in Europe, and the Esquimaux in
America, corresponding to the arctic fauna (400), and
like it, identical on the three continents, having for its
southern limit the region of trees (422). In Africa,
we have the Hottentot and Negro races, in the south
and central portions respectively, while the people of
northern Africa are allied to their neighbors in Europe ;
just as we have seen to be the case with the zoologi-
cal fauna in general (403). The inhabitants of New
Holland, like its animals, are the most grotesque and un-
couth of all races (433).

452. The same arrangement holds good elsewhere,
though not always in so remarkable a degree. In America,
especially, while the aboriginal race is as well distinguished
from other races as is its flora, the minor divisions are not
so decided. Indeed, the facilities, or sometimes we might
rather say necessities, arising from the varied supplies of

CONCLUSIONS. 181

animal and vegetable food in the several regions, might be
expected to involve, with his corresponding customs and
modes of life, a difference in the physical constitution of
man, which would contribute to augment any primeval dif-
ferences. It could not indeed be expected, that a people
constantly subjected to cold, like the people of the North,
and living almost exclusively on fish, which they cannot
obtain without great toil and peril, should present the same
characteristics, either bodily or mental, as those who idly
regale on the spontaneous bounties of tropical vegetation.

16

CHAPTER FOURTEENTH.

GEOLOGICAL SUCCESSION OF ANIMALS ; OR, THEIR
DISTRIBUTION IN TIME.

SECTION I.

STRUCTURE OF THE EARTH'S CRUST.

453. THE records of the Bible, together with human tra-
dition, teach us that man and the animals associated with
him were created by the word of God ; " the Lord made
heaven and earth, the sea, and all that in them is ; ' and
this truth is confirmed by the revelations of science, which
unequivocally indicate the direct interventions of creative
power.

454. But man and the animals which now surround him
are not the only kinds which have had a being. The surface
of our planet, anterior to their appearance, was not a desert.
There are, scattered through the crust of the earth, numerous
animal and vegetable remains, which show that the earth
had been repeatedly supplied with, and long inhabited by
animals and plants altogether different from those now
living.

455. In general, their hard parts are the only relics of
them which have been preserved, such as the skeleton and
teeth of Vertebrates ; the shells of the Mollusks and Radiata ;

STRUCTURE OF THE EARTH'S CRUST. 183

the shields of the Crustaceans, and sometimes the wing-cases
of Insects. Most frequently they have lost their original
chemical composition, and are changed into stone ; and
hence the name of petrifactions or fossils, under which lat-
ter term are comprehended all the organized bodies of
former epochs, obtained from the earth's crust.

456. The study of these remains and of their position in
the rocks constitutes PALEONTOLOGY ; one of the most essen-
tial branches of Zoology. Their geological distribution, or
the order of their successive appearance, namely, the dis-
tribution of animals in time, is of no less importance than
the geographical distribution of living animals, of which we
have treated in the preceding chapter. To obtain an idea
of the successive creations, and of the stupendous length of
time they have required, it is necessary to sketch the prin-
cipal outlines of Geology.

457. The rocks * which compose the crust of our globe
are of two kinds :

1. The Massive Rocks, called also Plutonic or Igneous
Rocks, which lie beneath all the others, or have some-
times been forced up through them, from beneath. They
were once in a melted state, like the lava of the present
epoch, and on cooling at the surface formed the original
crust of the globe of granite, porphyry, basalt, &c.

2. The Sedimentary or Stratified Rocks, called also
Neptunian Rocks, which have been deposited in water, in
the same manner as modern seas and lakes deposit sand and
mud on their shores, or at the bottom.

458. These sediments have been derived partly from the
disintegration of the older rocks, and partly from the decay
of plants and animals. The materials being disposed in

* Rocks, in a geological sense, include all the materials of the earth,
the loose soil and gravel, as well as the firm rock.

184 GEOLOGICAL SUCCESSION OF ANIMALS.

layers or strata have become, as they hardened, limestones,
slates, marls, or grits, according to their chemical and me-
chanical composition, and contain the remains of the animals
and plants which were scattered through the waters.*

459. The different strata, when undisturbed, are ar-
ranged one above the other in a horizontal manner, like
the leaves of a book, the lowest being the oldest. In conse-
quence of the commotions which the crust of the globe
has undergone, many points of its surface have been eleva-
ted to great heights, in the form of mountains ; and hence
it is that fossils are sometimes found at the summit of the
highest mountains, though the rocks containing them were
originally formed at the bottom of the sea. But even when
folded, or partly broken, their relative age may still be
determined by an examination of the ends of the upturned
strata, where they appear or crop out in succession, at the
surface, or on the slopes of mountains, as seen in the dia-
gram (Fig. 154).

460. The sedimentary rocks are the only ones which
have been found to contain animal and vegetable remains.
They are found imbedded in the sediment, just as we
should find them in the mud now deposited at the bottom of
the sea, if laid dry. The strata containing fossils are nume-
rous. The comparison and detailed study of them belongs

* Underneath the deepest strata containing fossils, between these and the
Plutonic rocks, are generally found very extensive layers of slates without
fossils (gneiss, mica-slate, talcose-slate), though stratified, and known to
the geologist under the name of Metamorphic Rocks (Fig. 154, M), being
probably sedimentary rocks which have undergone considerable changes.
The Plutonic rocks, as well as the metamorphic rocks, are not always con-
fined to the lower levels, but they are often seen rising to considerable
heights, and forming many of the loftiest peaks of the globe. The former
also penetrate, in many cases, like veins, through the whole mass of the
stratified and metamorphic layers, and expand at the surface ; as is the case
with the trap dykes, and as lava streams actually do now (Fig. 154, T,L).

STRUCTURE OF THE EARTH S CRUST.

185

to Geology, of which it forms an essential part. A group of
strata extending over a certain geographical extent, all of
which contain some fossils in common, no matter what may be
the chemical character of the rock, whether it be limestone,
sand or clay, is termed a geological Formation. Thus, the
coal beds, with the intervening slates and grts, and the
masses of limestone in which they are often imbedded,
constitute but one formation, the carboniferous formation.

461. Among the stratified rocks we distinguish ten prin-
cipal Formations, each of which indicates an entirely new
era in the earth's history ; while each of the layers which
compose a formation indicates but some partial revolution.
Proceeding from below upwards, they are as follows, as in-
dicated in the cut, and also in the lower diagram on the
frontispiece.

Fig. 154.

1st. The Lower Silurian. This is a most extensive
formation, no less than eight stages of which have been
made out by Geologists in North America, composed of
various limestones and sandstones.*

* 1. Potsdam Sandstone; 2. Calciferous Sandstone; 3. Chrzy Lime-
stone; 4. Bird's-eye Limestone ; 5. Black River Limestone ; 6. Trentoii
Limestone; 7. Utica Slate ; 8. Hudson River Group ; being all found in
the western parts of the United States.

16*

186 GEOLOGICAL SUCCESSION OF ANIMALS.

2d. The Upper Silurian. It is also a veiy extensive
formation, since about ten stages of it are found in the
State of New York.*

3d. The Devonian, including in North America no less
than eleven stages. t It occurs also in Russia and Scotland,
where it was first made out as a peculiar formation.

4th. The Carboniferous Formation, consisting of three
grand divisions. |

5th. The Trias, or Saliferous Formation which, contain-
ing the richest deposits of Salt on the continent of Europe,
comprises three stages,^ to one of which the Sandstone of
the Connecticut valley belongs.

6th. The Oolitic Formation, only faint traces of which
exist on the continent of America. It comprises at least four
distinct stages. ||

7th. The Cretaceous or Chalk Formation, of which three
principal stages have been recognized, two of which are
feebly represented in this country, in the Southern and Mid-
dle States.

8th. The Loiver Tertiary or Eocene, very abundant in the
Southern States of the Union, and to which belong the
coarse limestone of Paris, and the London clay in England.

* 1. Oneida Conglomerate ; 2. Medina Sandstone ; 3. Clinton Group ;
4. Niagara Group ; 5. Onondaga Salt Group ; 6. Water Limestone ;
7. Pentamerus Limestone ; 8. Delthyris Shaly Limestone ; 9. Encrinal
Limestone ; 10. Upper Pentamerus Limestone.

t 1. Oriskany Sandstone; 2. Cauda-Galli Grit; 3. Onondaga Lime-
stone; 4. Corniferous Limestone; 5. Marcellus Shale; 6. Hamilton
Group; 7. Tully Limestone; 8. Genesee Slate; 9. Portage Group;
10. Chemung Group ; 11. Old Red Sandstone.

I I. The Permian, extensively developed in Russia, especially in the
government of Perm; 2. The coal measures, containing the rich deposits
of coal in the Old and New World ; 3. The Magnesian Limestone of
England.

§ 1. New Red Sandstone ; 2. Muschelkalk ; 3. Keuper.

II 1. The Lias; 2. The Lower Oolite ; 3. The Middle Oolite ; 4. The
Upper Oolite.

STRUCTURE OF THE EARTH'S CRUST. 187

9th. The Upper Tertiary or Miocene , and Pleiocene,
found also in the United States, as far north as Martha's
Vineyard, and very extensive in Southern Europe, as well
as in South America.

10th. The Drift, forming the most superficial deposits,
and extending over a large portion of the northern coun-
tries in both hemispheres.

We have thus more than forty distinct layers already
made out, each of which marks a distinct epoch in the
earth's history, indicating a more or less extensive and
important change in the condition of its surface.

462. All the formations are not always found, or are not
developed to the same extent, in all places. It is the same
with the several strata of which they are composed. In
other words, the layers of the earth's crust are not continuous
throughout, like the coats of an onion. There is no place on
the globe where, if it were possible to bore down to its
centre, all the strata would be found. It is easy to under-
stand how this must be so. Since irregularities in the
distribution of water upon the hard crust have, necessarily,
always existed to a certain extent, portions of the earth's
surface must have been left dry at every epoch of its
history, gradually forming large continents and islands, as
the changes were multiplied. And since the rocks were
formed by the subsidence of sediment in water, no rocks
would be formed except in regions then covered by water;
they would be thickest at the parts where most sediment
was deposited, and gradually thin out towards their circum-
ference. We may therefore infer, that all those portions of
the earth's surface which are destitute of a certain formation
were dry land, during that epoch of the earth's history to
which such formation relates, excepting, indeed, where
the rocks have been subsequently removed by the denuding
action of water or other causes.

188 GEOLOGICAL SUCCESSION OF ANIMALS.

463. Each formation represents an immense period of
time, during which the earth was inhabited by successive
races of animals and plants, whose remains are often found,
in their natural position, in the places where they lived and
died, not scattered at random, though sometimes mixed to-
gether by currents of water, or other influences, subsequent
to the time of their interment. From the manner in which
the remains of various species are found associated in the
rock, it is easy to determine whether the animals to which
these remains belonged lived in the water, or on land, on the
beach or in the depths of the ocean, in a warm or in a cold
climate. They will be found associated in just the same
way as animals that live under similar influences at the
present day.

464. In most geological formations, the number of spe-
cies of animals and plants found in any locality of given
extent, is not below that of the species now living in an
area of equal extent ; for though, in some deposits, the vari-
ety of the animals contained may be less, in others it is
greater than that on the present surface. Thus, the coarse
limestone in the neighborhood of Paris, which is only one
stage of the lower tertiary, contains not less than 1200 spe-
cies of shells ; whereas the species now living in the Mediter-
ranean do not amount to half that number. Similar relations
may be pointed out in America. Mr. Hall, one of the geolo-
gists of the New York Survey, has described, from the Tren-
ton limestone (one of the ten stages of the lower Silurian), 170
species of shells, a number almost equal to that of all the
species found actually living on the coast of Massachusetts.

465. Nor was the number of individuals less than at
present. Whole rocks are entirely formed of animal re-
mains, particularly by corals and shells. So, also, coal is
composed of the remains of plants. If we consider the slow-
ness with which corals and shells are formed, it will give us

AGES OF NATURE. 189

some faint notion of the vast series of ages that must have
elapsed in order to allow the formation of those rocks, and
their regular deposition, under the water, to so great a thick-
ness. If, as all things combine to prove, this deposition took
place in a slow and gradual manner in each formation, we
must conclude, that the successive species of animals found
in them followed each other at long intervals, and are not
the work of a single epoch.

466. It was once believed that animals were successively
created in the order of their relative perfection ; so that
the most ancient formations contained only animals of the
lowest grade, such as the Polyps, the Echincderms, to
which succeeded the Mollusks, then the Articulated Ani-
mals, and last of all, the Vertebrates. This theory, how-
ever, is now untenable ; since fossils belonging to each of
the four departments have been found in the fossiliferous de-
posits of every age. Indeed, we shall see that even in the
lower Silurian formation there exist not only Polyps and other
Radiata, but also numerous Mollusks, Trilobites (belonging
to the Articulata), and even Fishes.

SECTION II.

AGES OF NATURE.

467. Each formation, as has been before stated (460),
contains remains peculiar to itself, which do not extend
into the neighboring deposits above or below it. Still there
is a connection between the different formations, more strong
in proportion to their proximity to each other. Thus, the
animal remains of the chalk, while they differ from those of
all other formations, are nevertheless much more nearly re-
lated to those of the oolitic formation, which immediately

190 GEOLOGICAL SUCCESSION OF ANIMALS.

precedes, than to those of the carboniferous formation, which
is much more ancient ; and in the same manner, the fossils
of the carboniferous group approach more nearly to those of
the Silurian formation, than to those of the Tertiary.

468. These relations could not escape the observation of
naturalists, and indeed they are of great importance for
the true understanding of the development of life at the sur-
face of our earth. And, as in the history of man, several
grand periods have been established, under the name of
Ages, marked by peculiarities in his social and intellectual
condition, and illustrated by cotemporaneous monuments,
so, in the history of the earth also, are distinguished several
great periods, which may be designated as the various Ages
of Nature, illustrated in like manner by their monuments,
the fossil remains, which, by certain general traits stamped
upon them, clearly indicate the eras to which they belong.

469. We distinguish four Ages of Nature, corresponding
to the great geological divisions, namely :

1st. The Primary or Paleozoic Age, comprising the lower
Silurian, the upper Silurian, and the Devonian. During this
age there were no air-breathing animals. The fishes were
the masters of creation. We may therefore call it the Reign
of Fishes.

2d. The Secondary Age, comprising the carboniferous
formation, the Trias, the oolitic, and the cretaceous forma-
tions. This is the epoch in which air-breathing animals first
appear. The reptiles predominate over the other classes,
and we may therefore call it the Reign of Reptiles.

3d. The Tertiary Age, comprising the tertiary formations.
During this age, terrestrial mammals, of great size, abound.
This is the Reign of Mammals.

4th. The Modern Age, characterized by the appearance
of the most perfect of all created beings. This is the Reign
of Man.

AGES OF WATUKE.

191

Let us review each of these four Ages of Nature, with re-
ference to the diagram at the beginning of the volume.

470. THE PALEOZOIC AGE. Reign of Fishes. — The
paleozoic fauna, being the most remote from the present
epoch, presents the least resemblance to the animals now
existing, as will easily be perceived by a glance at the fol-

Fig. 155.

lowing sketches (Fig. 155). In no other case do we meet
with animals of such extraordinary shapes, as in the strata
of the Paleozoic age.

471. We have already stated (466) that there are found,
in each formation of the primary age, animal remains of all
the four great departments, namely, vertebrates, articulata,
mollusks, and radiata. We have now to examine to what
peculiar classes and families of each department these re-
mains belong, with a view to ascertain if any relation

192 GEOLOGICAL SUCCESSION OF ANIMALS.

between the structure of an animal, and the epoch of its first
appearance on the earth's surface may be traced.

472. As a general result of the inquiries hitherto made, it
may be stated that the paleozoic animals belong, for the
most part, to the lower divisions of the different classes.
Thus, of the class of Echinoderms, we find scarcely any
but Crinoids, which are the least perfect of the class. We
have represented, in the above sketches, several of the most
curious forms,* as well as of the Polyps, of which there are
some quite peculiar types from the Trenton limestone and
from the Black River limestone.

473. Of the Mollusks, the bivalves or Acephala are nu-
merous, but for the most part belong to the Brachiopoda,
that is to say, to the lowest division of the class, including
mollusks with unequal valves having peculiar appendages
in the interior. The Leptcena alternata (b) which is found
very abundantly in the Trenton limestone is one of these
shells. The only fossils yet found in the Potsdam sandstone,
the oldest of all fossiliferous deposits, belong also to this
family (Lingula prima, a). Besides this, there are also
found some bivalves of a less uncommon shape (Avicula
decussata, e).

474. The Gasteropods are less abundant ; some of them
are of a peculiar shape and structure (Bucania expansa,/;
Euomphalus hemisphcericus, c). Those more similar to
our common marine snails have all an entire aperture ;
those with a canal being of a more recent epoch.

475. Of the Cephalopods we find some genera not less
curious, part of which disappear in the succeeding epochs ;

* (i) Cyathocrinus ornatissimus, Hall ; (j) Melocrinus Amphora, Goldf.
(k) Cariocrinus ornatus, Say; (/) Columnaria alveolatv ; (m) Cyatho-
phyllum quadrigeminum, Goldf.; (n, o) Caninia Jlexuosa ; (p) Cheetetes
lycoperdon.

AGES OF NATURE.

193

such, in particular, as those of the straight, chambered shells
called Orthoceratites, some of which are twelve feet in
length (Orthoceras fusiforme, g). There are also found
some of a coiled shape, like the Ammonites of the secondary
age, but having less complicated partitions ( Trocholites
ammonius, d). The true cuttle-fishes, which are the highest
of the class, are not yet found. On the contrary, the Bryo-
zoa, which have long been considered as polyps, but which,
according to all appearances, are mollusks of a very low
order, are veiy numerous in this epoch.

476. The Articulata of the Paleozoic age are mostly
Trilobites, animals which evidently belong to the lower
order of the Crustaceans (Fig. 156). There is an incom-
pleteness and want of development, in the form of their
body, that strongly reminds us of the embryo among the
crabs. A great many genera have already been discovered.

tt

d ^KYVV^^S-^ "I%£3P e

Fig. 156.

We may consider as belonging to the more extraordinary,
the forms here represented, (Harpes, a ; Arges, 1) ; Brontes,
c ; and Platynotus, d] ; the latter, as well as the Isotelus,
the largest of all, being peculiar to the Paleozoic deposit of
this country. Some others seem more allied to the crusta-
ceans of the following ages, but are nevertheless of a very
extraordinary form, as Eurypterus remipes (e). There
are also found, in the Devonian, some very large Ento-
mostraca. The class of Worms is represented only by a

17

194

GEOLOGICAL SUCCESSION OF ANIMALS.

few Serpulae, which are marine worms, surrounded by a
solid sheath. The class of Insects is entirely wanting.

477. The inferiority of the earliest inhabitants of our
earth appears most striking among the Vertebrates. There
are as yet neither reptiles, birds, nor mammals. The fishes,
as we have said, are the sole representatives of this division
of animals.

478. But the fishes of that early period were not like
ours. Some of them had the most extraordinary forms, so
that they have been often mistaken for quite different ani-
mals; for example, the Pterichthys (a), with its two wing-

a

Fig. 157.

like appendages, and also the Coccosteus (&) of the same de-
posit, with its large plates covering the head and the ante-
rior part of the body. There are also found remains of
shark's spines (e), as well as palatal bones (rf), the latter of a
very peculiar kind. Even those fishes which have a more
regular shape, as the Dipterus (c), have not horny scales
like our common fishes, but are protected by a coat of bony
plates, covered with enamel, like the gar-pikes of the
American rivers. Moreover, they all exhibit certain char-
acteristic features, which are very interesting in a physio-
logical point of view. They all have a broad head, and a
tail terminating in two unequal lobes. What is still more
curious, the best preserved specimens show no indications

AGES OF NATURE. 195

of the bodies of vertebrae, but merely the spinous processes ;
from which it must be infered that the body of the vertebra
was cartilaginous, as it is in our Sturgeons.

479. Recuring to what has been stated on that point,
in Chapter Twelfth, we thence conclude, that these ancient
fishes were not so fully developed as most of our fishes,
being, like the Sturgeon, arrested, as it were, in their devel-
opment ; since we have shown that the Sturgeon, in its or-
ganization, agrees, in many respects, with the Cod or
Salmon in their early age.

480. Finally, there was, during the Paleozoic age, less
variety among the animals of the different regions of the
globe ; and this may be readily explained by the peculiar
configuration of the earth at that epoch. Great mountains
did not then exist ; there were neither lofty elevations nor
deep depressions. The sea covered the greater part, if not
the whole, of the surface of the globe ; and the animals
which then existed, and whose remains have been preserved,
were all, without exception, aquatic animals, breathing by
gills. This uniform distribution of the waters impressed a
very uniform character upon the whole Animal Kingdom.
Between the different zones and continents, no such strange
contrasts of the different types existed as at the present
epoch. The same genera, and often the same species were
found in the seas of America, Europe, Asia, Africa, and
New Holland ; from whence we must conclude that the
climate was much more uniform than at the present day.
Among the aquatic population, no sound was heard. All
creation was then silent.

481. THE SECONDARY AGE. Reign of Reptiles. — The
Secondary age displays a greater variety of animals as well
as plants. The fantastic forms of the Paleozoic age disap-
pear, and in their place we see a greater symmetry of
shape. The advance is particularly marked in the series of

196 GEOLOGICAL SUCCESSION OF ANIMALS.

vertebrates. The fishes are no longer the sole representa-
tives of that department. Reptiles, Birds, and Mammals
successively make their appearance, but the Reptiles are
preponderant, particularly in the oolitic formation ; on which
account we have called this the Reign of Reptiles.

482. The carboniferous formation is the most ancient of
the Secondary age. Its fauna shows, in various respects, a
great analogy with that of the Paleozoic epoch, especially
in its Tribolites and Mollusks.* Besides these, we meet
here with the first air-breathing animals, which are Insects
and Scorpions. At the same time, land-plants first make
their appearance, namely, ferns of great size, club-mosses,
and other fossil plants. This corroborates what has been
already said concerning the intimate connection that exists,
and from all times has existed, between animals and the
land-plants (399). The class of Crustaceans has also im-
proved during the epoch of the coal. It is no longer com-
posed exclusively of Trilobites, but the horse-shoe crabs also
appear, with other gigantic forms. Some of the Mollusks
seem also to approach those of the Oolitic period, particu-
larly the Bivalves.

483. In the Trias period, which immediately succeeds
the Carboniferous, the fauna of the Secondary age acquires
its definitive character ; here the Reptiles first appear.
They are huge Crocodilian animals, belonging to a pecu-
liar order, the Rhizodonts (Protosaurus, Notosaurus, and
Labyrintliodori). The well-known discoveries of Professor

* This circumstance, in connection with the absence of Reptiles, has
caused the coal-measures to be generally referred to the Paleozoic epoch.
But there are other reasons which induce us to unite the carboniferous
period with the secondary age, especially when considering that here the
land animals first appear, whereas, in the Paleozoic age, there are only
marine animals, breathing by gills ; and also, that a luxuriant terrestrial
vegetation was developed at that epoch.

AGES OF NATURE.

197

Hitchcock, in the red sandstone of the Connecticut, have
made us acquainted with a great number of birds' tracks

a Fig. 158. b c

(Fig. 157, #, &), belonging to this epoch, for the most part in-
dicating birds of gigantic size. These impressions, which he
has designated under the name of Ornithichnites, are some
of them eighteen inches in length, and five feet apart, far
exceeding in size the tracks of the largest ostrich. Other
tracks, of a very peculiar shape, have been found in the red
sandstone of Germany and in Pennsylvania. They were
probably made by Reptiles, which have been called Chei-
rotherium, from the resemblance of the track to a hand (c).
The Mollusks, Articulates, and Radiates of this period,
approach to the fauna of the succeeding period.

484. The fauna of the Oolitic formation is remarkable for
the great number of gigantic Reptiles which it contains. In

a

this formation we find those enormous Amphibia, known
under the name Ichthyosaurus, Plesiosaurus, Megalosaurus,
and Iguanodon. The first, in particular, the Icthyosaurus
(Fig. 159, a), greatly abounded on the coast of the conti-
nents of that period, and their skeletons are so well pre-
served, that we are enabled to study even the minutest
details of their structure, which differs essentially from that
of the Reptiles of the present day. In some respects they
form an intermediate link between the Fishes and Mammals,

198 GEOLOGICAL SUCCESSION OF ANIMALS.

and may be considered as the prototypes of the Whales, hav-
ing, like them, limbs in the form of oars. The Plesiosaurus
, agrees, in many respects, with the Ichthyosaurus, in its

structure, but is easily distin-
guished by its long neck, which
resembles somewhat the neck of
some of our birds. A still more
extraordinary Reptile is the
Pterodactylus (Fig. 160), with
its long fingers, like those of
Fig. 160. a bat, and which is thought

to have been capable of flying.

485. It is also in the upper stages of this formation that
we first meet with Tortoises. Here also we find impres-
sions of several families of insects, (Libellulce, Coleoptera,
Ichneumons, <^c.) Finally, in these same stages, the slates
of Stonesfield, the first traces of Mammals are found,
namely, the jaws and teeth of animals having some re-
semblance to the Opossum.

486. The department of Mollusks is largely represented
in all its classes. The peculiar forms of the primary age
have almost all disappeared, and are replaced by a much
larger quantity of new forms. Of the Brachiopods only one

bed

Fig. 161.

type is very abundant, namely, that of the Terebratula
(Fig. 161, a). Among the other Bivalves there are many
peculiar forms, as the Goniomya (Z>), and the Trigonia (c).
The Gasteropods display a great variety of species, and also
the Cephalopods, among which the Ammonites are the

AGES OF NATURE.

199

most prominent (d). There are also found, for the first
time, numerous repre-
sentatives of the Cut-
tle-fishes, under the
form of Belemnites
(Fig. 162), an extinct
type of animals, sur- Fig. 162. 6

rounded by a sheath, and containing in their interior a
peculiar bone, somewhat similar to the bone of the Sepia,
and which commonly is the only preserved part (J).

487. The variety is not less remarkable among the
Radiates. There are to be found representatives of all the
classes ; even traces of Jelly-fishes have been made out in
the slate of Solenhofen, in Bavaria. The Polyps were
very abundant at that epoch, especially in the upper stages,
one of which has received the name of Coral-rag. Indeed,
there are to be found whole reefs of corals in their natural
position, similar to those which are to be seen in the islands

a

Fis:. 163.

of the Pacific. Among the most remarkable types of stony
Polyps, may be named the fan-like Lobophyllia (L.flabel-
lum, a), and various forms of tree-corals (Lithodendron
2iseudostylina, b). But the greatest variety exists among the
Echinoderms. The Crinoids are not quite so numerous as
in former ages. Among the most abundant are the Pent.a-
crlnus (c). There are also already found Comatula-like
animals, that is to say, free Crinoids, (Pterocoma pinnata, d).

200

GEOLOGICAL SUCCESSION OF ANIMALS,

Many Star-fishes are likewise to be found in the various
stages of this formation. Finally, there is an extraordinary
variety of Echini, among them Cidaris (e), with large spines,
and several other types not found before, as, for example,
the Disaster (/) and the Nudeolites (g).

488. The fauna of the Cretaceous period bears the
same general characters as the Oolitic, but with a more
marked tendency towards the actual forms. Thus the
Ichthyosauri and Plesiosauri, that characterize the pre-
ceding epoch, are succeeded by gigantic Lizards, more
nearly approaching the Reptiles of the present day. Among
the Mollusks, a great number of new forms appear, espe-
cially among the Cephalopods,* some of which resemble

d

f

c Fig. 164. e

the Gasteropods in their shape, but are nevertheless
chambered. The Ammonites themselves are quite as

b Fig. 165."

numerous as in the Oolitic period, and are in general
much ornamented (a). The Acephala furnish us also
with peculiar types, not found elsewhere, Ma gas («),

* (a) Ammonites; (b) Crioceras ; (c) Scaphites ; (d) Ancyloceras ;
(e) Hamites; (/) Baculites ; (§•) Turrilites,

AGES OF NATURE.

201

the Jnoceramus (5), the Hippurites (c), and peculiar Spon-
dyli, with long spines (d). There is also a great variety of
Gasteropods, among which are some peculiar forms of Pleu-

b c d e

a

Fig. 1 66.

rotomaria (e). The Radiates are not inferior to the others
in variety.*

489. TERTIARY AGE. Reign of Mammals. — The most
significant characteristic of the Tertiary faunas is their
great resemblance to those of the present epoch. The ani-
mals belong in general to the same families, and mostly to the
same genera, differing only as to the species. And the spe-
cific differences are sometimes so slightly marked, that a
considerable familiarity with the subject is required, in order
readily to detect them. Many of the most abundant
types of former epochs have now disappeared. The
changes are especially striking among the Mollusks, the
two great families of Ammonites and Belemnites, which
present such an astonishing variety in the Oolitic and Creta-
ceous epochs, being now completely wanting. Changes of
no less importance take place among the Fishes, which are
for the most part covered with horny scales, like those of
the actual epoch, while in earlier ages they were generally
covered with enamel. Among the Radiata, we see the
family of Crinoids reduced to a very few species, while, on
the other hand, a great number of new Star-fishes and Sea-
urchins make their appearance. There are besides, innu-
merable remains of a very peculiar type of animals, almost

* (a) Diploctenium cordalum ; (b) Marsupites ; (c) Salenia ; (d) Gale-
rites : (e) Micraster cor-anguinum.

202

GEOLOGICAL SUCCESSION OF ANIMALS.

unknown to the former ages, as well as to the actual period.
They are little-chambered shells, known to
geologists under the name of Nummulites,
from their coin-like appearance, and form very
extensive layers of rocks (Fig. 167).

Fig. 167.

490. But what is more important, in a philosophical point
of view, is, that the aquatic animals are no longer predomi-
nant in the Creation. The great marine or amphibian
reptiles give place to numerous mammals of great size.
For which reason we have called this age the Reign of
Mammals. Here are also found the first distinct remains
of fresh- water animals.

491. The lower stage of this formation is particularly
characterized by great Pachyderms, among which we may
mention the Paleotherium and Anoplotherium, which have
acquired such celebrity from the researches of Cuvier.
These animals, among others, abound in the Tertiary form-
ations of the neighborhood of Paris. The Paleotheriums, of

Fig. 168. Fig. 169.

which several species are known, are the most common ;
they resemble (Fig. 168), in some respects, the Tapirs,
while the Anoplotheriums are more slender animals (Fig.
169). On this continent are found the remains of a most ex-
traordinary animal of gigantic size, the Basilosaurus, a true
cetacean. Finally, in these stages, the earliest remains of
Monkeys have been detected.
492. The fauna of the upper stage of the Tertiary forma-

AGES OF NATURE. 203

tion approaches yet more nearly to that of the present
epoch. Besides the Pachyderms, that were also predomi-
nant in the lower stage, we find numbers of carnivorous
animals, some of them much surpassing in size the lions
and tigers of our day. We meet also gigantic Edentata,
and Rodents of great size.

493. The distribution of the Tertiary fossils also reveals
to us the important fact, that in this epoch, animals of the
same species were circumscribed in much narrower limits
than before. The earth's surface, highly diversified by
mountains and valleys, was divided into numerous basins,
which, like the Gulf of Mexico, or the Mediterranean of this
day, contained species not found elsewhere. Such was the
basin of Paris, that of London, and on this continent, that of
South Carolina.

494. In this limitation of some types within certain bounds,
we distinctly observe another approach to the actual con-
dition of things, in the fact that certain groups of animals
which occur only in particular regions are found to have
already existed in the same regions during the Tertiary
epoch. Thus the Edentata are the predominant animals
in the fossil fauna of Brazil as well as in its actual fauna ;
and Marsupials were formerly as numerous in New Hol-
land as they now are, though in general of much larger size.

495. THE MODERN EPOCH. Reign of Man. — The
Present epoch succeeds to, but is not a continuation of, the
Tertiary age. These two epochs are separated by a great
geological event, traces of which we see everywhere around
us. The climate of the northern hemisphere, which had
been, during the Tertiary epoch, considerably warmer than
now, so as to allow of the growth of palm-trees in the tem-
perate zone of our time, became much colder at the end of
this period, causing the polar glaciers to advance south, much
beyond their previous limits. It was this ice, either floating

204 GEOLOGICAL SUCCESSION OF ANIMALS.

like icebergs, or, as there is still more reason to believe,
moving along the ground, like the glaciers of the present
day, that, in its movement towards the South, rounded and
polished the hardest rocks, and deposited the numerous
detached fragments brought from distant localities, which
we find everywhere scattered about upon the soil, and
which are known under the name of erratics, boulders, or
greyheads. This phase of the earth's history has been
called, by geologists, the Glacial or Drift period.

496. After the ice that carried the erratics had melted
away, the surface of North America and the North of Europe
was covered by the sea, in consequence of the general
subsidence of the continents. It is not until this period
that we find, in the deposits known as the diluvial or pleis-
tocene formation, incontestable traces of the species of ani-
mals now living.

497. It seems, from the latest researches of Geologists,
that the animals belonging to this period are exclusively
marine ; for, as the northern part of both continents was
covered to a great depth with water, and only the summits
of the mountains were elevated above it, as islands, there
was no place in our latitudes where land or fresh-water
animals could exist. They appeared therefore at a later
period, after the water had again retreated ; and, as from
the nature of their organization, it is impossible that they
should have migrated from other countries, we must con-
clude that they were created at a more recent period than
our marine animals.

498. Among these land animals which then made their
appearance, there were representatives of all the genera
and species now living around us, and besides these, many
types now extinct, some of them of a gigantic size, such as
the Mastodon, the remains of which are found in the upper-
most strata of the earth's surface, and probably the very

CONCLUSIONS.

205

last large animal which became extinct before the creation
of man.*

Fig. 170.

499. It is necessary therefore, to distinguish two periods
in the history of the animals now living ; one in which the
marine animals were created, and a second, during which
the land and fresh-water animals made their appearance,
and at their head MAN.!

CONCLUSIONS.

500. From the above sketch it is evident that there is a
manifest progress in the succession of beings on the surface

* The above diagram is a likeness of the splendid specimen disin-
tered at Newburg, N. Y"., now in the possession of Dr. J. C. Warren,
in Boston ; the most complete skeleton which has ever been discovered.
It stands nearly twelve feet in height, the tusks are fourteen feet in length)
and nearly every bone is present, in a state of preservation truly wonderful.

t The former of these phases is indicated in the frontispiece, by a nar-
row circle, inserted between the upper stage of the Tertiary formation and
the Reign of Man properly so called.
13

206 GEOLOGICAL SUCCESSION OF ANIMALS.

of the earth. This progress consists in an increasing simi-
larity to the living fauna, and among the Vertebrates, espe-
cially, in their increasing resemblance to Man.

501. But this connection is not the consequence of a
direct lineage between the faunas of different ages. There
is nothing like parental descent connecting them. The
Fishes of the Paleozoic age are in no respect the ancestors
of the Reptiles of the Secondary age, nor does Man descend
from the Mammals which preceded him in the Tertiary age.
The link by which they are connected is of a higher
and immaterial nature ; and their connection is to be sought
in the view of the Creator himself, whose aim, in forming
the earth, in allowing it to undergo the successive changes
which Geology has pointed out, and in creating successively
all the different types of animals which have passed away,
was to introduce Man upon the surface of our globe.
Man is the end towards which all the animal creation
has tended, from the first appearance of the first Paleozoic
Fishes.

502. In the beginning His plan was formed, and from it
He has never swerved in any particular. The same Being
who, in view of man's moral wants, provided and declared,
thousands of years in advance, that " the seed of the woman
shall bruise the serpent's head," laid up also for him in the
bowels of the earth, those vast stores of granite, marble,
coal, salt, and the various metals, the products of its several
revolutions ; and thus was an inexhaustible provision made
for his necessities, and for the development of his genius,
ages in anticipation of his appearance.

503. To study, in this view, the succession of animals in
time, and their distribution in space, is therefore to become
acquainted with the ideas of God himself. Now, if the suc-
cession of created beings on the surface of the globe is the
realization of an infinitely wise plan, it follows that there

CONCLUSIONS. 207

must be a necessary relation between the races of ani-
mals, and the epoch at which they appear. It is necessary,
therefore, in order to comprehend Creation, that we com-
bine the study of extinct species with that of those now
living, since one is the natural complement of the other. A
system of Zoology will consequently be true, in proportion
as it corresponds with the order of succession among
animals.

END OF THE FIRST PART.

INDEX AND GLOSSARY.

Abdomen, the lower cavity of the
body, 17.

Abranclaates, without gills, xvii.

Acalepha, a class of Radiates many
species of which produce tingling
when handled.

Acephala, mollusks having no dis-
tinct head, like clams, xix.

Acoustic, pertaining to the sense of
hearing, 32.

Actinia, digestive apparatus of, 73.

Affinity, relationship, 6, 63.

Ages of Nature, 189.

Albumen, the white of egg, 108.

Alimentary canal, 73.

Alimentation, the process of nutri-
tion, 18.

Allantois, Allantoidian, 119.

Alligator, teeth of, 80.

Alternate reproduction, 127 ; conse-
quences of, 136 ; difference be-
tween, and metamorphosis, 137.

Amblyopsis spelaeus, 31.

Ammonites, xvii. 198, 200, 201.

Amnios, 120.

Amphibia, 71.

Amphipods, a family of crustaceans.

Amphioxus, its place, 148.

Amphiuma, 177.

Analogy, 6.

Anatifa, metamorphoses of, 145.

Ancyloceras, 200.

Animalcule, a minute animal, xix.

Animal heat, 96.

Animal life, 20 ; organs of, 20.

Animals, number of, 3.

Animals and plants, differences be-
tween, 17.

18*

Animate, possessed of conscious-
ness, 19.

Anoplotherium, 202.

Antenna, the jointed feelers of lob-
sters, insects, &c., 53.

Aorta, the great blood-vessel arising
from the heart, 90.

Aphides, reproduction of, 131.

Apophysis, a projection from the
body of a bone, 149.

Apparatus of motion, 48.

Aptera, wingless insects, xvii.

Aquatic, living in water.

Aqueous, like water.

Aqueous humor, 126.

Arctic fauna, 164.

Areolar tissue, 14.

Arges, 193.

Aristotle's lantern, 77.

Arm, different forms of, 59.

Artery, 90.

Articulates, composed of joints, like
the lobster or caterpillar ; number
of, 3.

Ascidia, bottle-shaped mollusks with-
out a shell.

Assimilation, the change of blood in-
to bone, muscle, &c. 96.

Astacus pellucidus, 31.

Asteridee, the family of star-fishes,
xviii.

Auditory, pertaining to the sense of
hearing, 32.

Auricle, a cavity of the heart, like a
little ear, 89.

Avicula decussata, 192.

Axolotl, 177.

210

INDEX AND GLOSSARY.

Baculites, 200.

Balanus, the barnacle, 144.

Basilosaurus, 202.

BatrachianSj the frog tribe, xvi.

Beak, 79.

Belemnites, 199, 201.

Bird-tracks, in red sandstone, 197.

Birds, number of, 3.

Bivalve, having two shells, like the

clam, 3.
Blastoderm, the embryonic germ,

111.

Blind-fishes, 31.
Blood, 86.
Boulders, 204.
Brachiopods, a class of mollusks,

xviii.
Brain, 21.
Branchiae, gills, 94.
Branchifers, univalve mollusks

breathing by gills, xviii.
Bronchi, tubes brandling from the

windpipe in the lungs, 93.
Brontes, 193.
Bryozoa, xviii. 193.
Bucania expansa, 192.

Calcareous, composed of lime, 51,

107.
Campanularia, reproduction of, 134,

139.

Canine teeth, 81.
Caninia flexuosa, 192.
Canker-worm, metamorphoses of,

144.

Cannon-bone, 60.
Capillary vessels, 88.
Carapace, the upper covering of the

crab or tortoise, 51.
Carbon, the basis of charcoal and

most combustibles, 17.
Carboniferous rocks, 186, 196.
Cariocrinus ornatus, 192.
Carnivora, animals feeding on flesh,

xvi. ; teeth of, 82.
Carpus, the wrist, 59.
Cartilage, gristle, 15.
Cartilaginous tissue, 14.
Cell, 13 ; nucleated, 14.
Cephalopods, mollusks with arms

surrounding the head, like the

cuttle-fish, xvii.

Cercaria, reproduction of, 129, 138.
Cerebral, pertaining to the brain, 21.
Cestracion Philippi, 171.
Cetaceans, marine animals which

nurse their young, like the whale,

porpoise, &c. xvi.

Chaetetes lycoperdon, 102.

Chalaza, the albuminous thread by
which the yolk of the egg is sus-
pended, 109.

Chambers of the eye, 26.

Cheirotherium, 197.

Chelonians, reptiles of the tortoise
tribe, xvi.

Chorion, 120.

Choroid, coat of the eye, 25.

Chrysalis, the insect in its passage
from the worm to the fly state,
143.

Chyle, 74.

Chyme, 75.

Cilia, microscopic hairs, like eye-
lashes, 57, 84, 87, 94.

Circulation, 86 ; great, 90 ; pulmo-
nary or lesser, 90 ; complete, 90 ;
incomplete, 91.

Cirrhipedes, Crustacea having curled
feelers, like the barnacles, fig. 145.

Clavicle, the collar-bone, 59.

Climbing, 68.

Coccosteus, 194.

Cold-blooded animals, 96.

Coleopterous, insects with hard
wing cases, like the dor-bug, 3.

Collar-bone, 59.

Columnaria alveolata, 102.

Comatula, metamorphosis of, 147,
148.

Constancy of species, 43.

Cornea, the transparent portion of
the eye, 25.

Corpuscles, minute bodies, 15.

Cossus ligniperda, muscles of, 53.

Cretaceous, or chalk formation, 186.

Cricoid, ring-like, 41.

Crinoid, lily-like star-fishes, xviii.

Crioceras, 200.

Crustacea, articulated animals hav-
ing a crust-like covering, like the
crab and horse-shoe ; heart of, 91.

Crypts, little recesses or sacs, 100.

Crystalline lens, 25.

Ctenoids, fishes which have the
edge of the scales toothed, xvi.

Ctenophori, soft, radiated animals,
moving by cilia, xix.

Cuttle-fish, jaws of, 78 ; heart of, 91 ;
metamorphosis of, 148 ; mode of
swimming, 71.

Cyathocrinus ornatissimus, 192.

Cyathophyllum quadrigeminum, 192.

Cycloids, fishes with smooth scales,
xvi.

INDEX AND GLOSSARY.

211

Deciduous, not permanent during a

lifetime, 426.
Deglutition, the act of swallowing-,

83.
Dentition, form and arrangement of

the teeth.
Department, a primary division of

the animal kingdom, xiv.
Development of the white-fish, 115.
Devonian rocks, 186.
Diaphragm, the partition between

the chest and abdomen, 50, 93.
Diastole, the dilatation of the heart,

90.

Digestion, 73.

Diploctenium cordatum, 201.
Dipterus, 194.

Disc, a more or less circular, flat-
tened body, iii.
Discophori, disc-shaped animals, like

the jelly-fish, xviii.
Distoma, reproduction of, 130 ; in

eye of the perch, 140.
Distribution of animals in time, 182.
Dodo, its disappearance, 178.
Dorsal cord, 113.
Dorsibranchiates, mollusks having

gills upon the back, xviii.
Drift, 187, 204.

Duck-barnacle. See Anatifa.
Dysaster, 200.

Ear, 32.

Echinoderms, radiate animals armed
with spines externally, like the
sea-urchin, xviii.

Echinus, the sea-urchin xviii ; jaws
of, 77 ; heart of, 91 ; mode of pro-
gression, 57.

Echinus sanguinolentus, metamor-
phosis of, 146.

Egg, 102 ; form of, 103 ; formation
of, 104 ; ovarian, 104 ; laying of,
105 ; composition of, 107 ; devel-
opment of, 109 ; of Infusoria, 141.

Elementary structure of organized
bodies, 12.

Embryo, the young animal before
birth, 9, 102 ; development of, 109.

Embryology, 102, 110 ; importance
of, 122.

Endosmose, 99. See Exosmose.

Engeena, a large ourang, 174.

Entomostraca, xvii.

Eocene formation, 1S6.

Ephyra, 133, 138.

Epidermis, the scarf-skin, 99.

Equivocal reproduction, 127.

Erratics, rolling stones, 204.

Euomphalus heniisphericus, 192.

Eurypterus remipes, 193.

Excretions, 101.

Exhalation, 99.

Exosmose and Endosmose, the pro-
cess by winch two fluids pass each
way, through a membrane which
separates them, so as to become
mingled, 99.

Eye, simple, 27 ; aggregate, 29 ;
compound, 30 ; destitution of, 31 ;
compared to a camera obscura, 27.

Fa^ette, a very small surface, 30.
Family, a group including several

genera, xiv.

Fauna, 154 ; distribution of, 161.
Femur, the thigh-bone, 63.
Fibula, the smallest of the two bones

of the leg, 63.
Fins, 70.
Fishes, number of, 3 ; heart of, 91 ;

reign of, 190, 191.
Fissiparous reproduction, propaga-

gation by fissure or division, 125.
Flight, 68.

Fluviatile, pertaining to rivers, 3.
Follicles, minute pouches, 100.
Formation, geological, 185.
Fossil, dug from the earth, applied to

the remains of animals and plants.
Function, the office which an organ

is designed to perform, 5.

Galeopithecus, its facilities for leap-
ins:, 69, 175.

Galerites, 201.

Gallinaceous, birds allied to the do-
mestic fowl, 161.

Gallop, 67.

Ganglions, scattered nervous mas-
ses, from which nervous threads
arise, 22.

Ganoids, fishes having large, bony,
enamelled scales, mostly fossil,
xvi.

Gasteropods, mollusks which crawl
by a flattened disc, or foot, on the
under part of the body, like the
snail, xvii.

Gastric juice, 75.

Gavial, a crocodile, with a long,
slender head.

Gemmiparous reproduction, propa-
gation by budding, 125.

General properties of organized
bodies, 11.

212

INDEX AND GLOSSARY.

Genus, xiv.

Geographical distribution of ani-
mals, 154.

Geological succession of animals,
182.

Germ, the earliest manifestation of
the embryo, 18, 111.

Germinative disc, 111 ; vesicle, 104 ;
dot, 104, 108.

Gestation, the period of carrying
youiiir, 106.

Gi'lls, 7, 94.

Glacial period, 204.

Glands, 100 ; salivary, 100.

Globules of chyle, 76 ; of blood, 86.

Glottis, 41.

Grallatores, birds with long legs for
wading, xvi.

Grand-nurses of Cercaria, 131.

Granivorous, birds feeding on grain.

Grit, coarse sandstone, 184.

Hamites, 200.

Harmony of organs, 82.

Harpes, 193.

Hearing, 31.

Heart, 89.

Herbivora, animals feeding on grass
and leaves, xvi.

Hibernation, torpid state of animals
during winter, 97.

Hippurites, 201.

Holothurians, soft sea-slugs, biche-
le-mar, xviii.

Homology, 6.

Humerus", the shoulder-bone, 69.

Hyaline matter, pure, like glass, 15.

Hydra, egg of, 104 ; propagation of,
125, 127.

Hydrogen, a gas which is the princi-
pal constituent of water, 17.

Hydroids, a family of polyps, xix.

Ichthyosaurus, 197, 200.

Icterus Baltimore, nest of, 46.

Igneous, that have been acted upon
by fire, 183.

Iguanodon, 197.

Inanimate, destitute of conscious-
ness, 19.

Incessores, perching birds, like birds
of prey, xv.

Incisor teeth, 81.

Incubation, hatching of eggs by the
mother, 107.

Infusoria, microscopic animals in-
habiting the water, not yet fully
arranged in their proper classes,

xix. ; motions of, 16 ; generation

of, 141.

Inoceramus, 201.

Inorganic, not made up of tissues, 11.
Insalivation, 83.
Instinct, 45.
Intelligence, 44.
Intercellular passages, 13.
Invertebrates, animals destitute of a

back-bone.
Iris, the colored portion of the eye,

25.
Isotelus, 193.

Jelly-fish. See Medusa.
Judgment, 44.

Labyrinthodon, 196.

Lacertans, animals of the lizard

tribe, xvi.
Lacteals, vessels which take up the

nutriment, 76.
Lamellibranchiates, mollusks having

gills arranged in sheets, like the

clam and oyster, xviii.
Larva, the caterpillar or worm state

of an insect.
Larynx, 41.

Layers of the embryo, 112.
Leaping, 67.
Leptsena alternata, 192.
Life, 11, 20.
Limbs, 38.

Limuea, parasites of, 129 - 31.
Lingula prima, 192.
Lithodendron pseudostylina, 199.
Liver, 101.

Lobopbyllia flabellum, 199.
Lobsters, mode of swimming, 70 ;

nervous system, 22.
Locomotion, 55 ; organs of, 58 ;

modes of, 64.
Lungs, 92.
Lymphatic vessels, 76.

Magas, 200.

Mammals, animals which nurse
their young, xvi. ; number of, 3 ;
reign of, 190, 201, 202.

Man, reign of, 190, 203 ; races of,
180 ; liis twofold nature, 1.

Manducata, insects furnished with
jaws, xvii.

Marchantia polymorpha, reproduc-
tion of, 135.

Marl, earth principally composed of
decayed shells and corals, 184.

Marsupials, animals with a pouch

INDEX AND GLOSSARY.

213

for carrying their young, as the
opossum ; gestation of, 151.

Marsupites, 5201.

Mastication, 77.

Mastodon, 204.

Matrix, the organ in which the em-
bryo is developed, 121.

Medulla oblongata, continuation of
the brain into the back-bone.

Medusa, jelly-like animals living in
the sea, xviii. ; development of,
132 ; digestive organs, 70.

Megalobatrachus, 177.

Megalosaurus, 197.

Melocrinus amphora, 192.

Memory, 44.

Menobfanchus, 169, 177.

Menopdma, 169, 177.

Merganser, an aquatic bird allied to
the goose, 42, 161.

Metacarpus, the wrist, 59.

Metamorphic rocks, 184.

Metamorphosis, 119, 142 ; of the silk-
worm, 143 ; canker-worm, 144 ;
duck-barnacle, 345; star-fish, 146;
comatula, 147.

Micraster cor-anguinum, 201.

Miocene formation, 187.

Modern age, 190, 203.

Molar teeth, 81.

Molecules, very minute particles,

Mollusks, soft animals of the snail
and oyster kind ; heart of, 90 ;
liver of, 101 ; number of, 3 ; meta-
morphosis of, 147.

Monkey, teeth of, 81.

Morioculus, mode of carrying eggs,
106.

Moulting, the shedding of feathers,
hair, &c. 98.

Muscles, 48 ; disposition of, in in-
sects, 53 ; in fishes, 54 ; in birds,
55.

Muscular tissue, 15.

Myxine glutinosa, its eye, 31.

Natatores, birds with webbed feet
for swimming, xvi.

Natica, tongue of, 78 ; heart of, 91.

Nautili, xvii.

Neptunian rocks, 183.

Nereis, jaws of, 78 ; gills of, 57 ; eye,
29.

Nervous system, 20 ; in mammals,
21 ; in articulates, 22 ; in crusta-
ceans, 22 ; in radiates, 23.

Nervous tissue, 15.

Nest of Baltimore oriole, 46 ; of tai-
lor bird, 46 ; of Ploceus, 47.

Nomenclature, the naming of ob-
jects and their classes, family,
&c.

Notosaurus, 196.

Nucleolites, 200.

Nucleolus, a little nucleus, 14.

Nucleus, a kernel, or condensed
central portion, 14.

Nudibranchiates, mollusks having
the gills floating externally, fig. 91.

Nummulites, 202.

Nurses, of Cercaria, 130 ; ants and
bees, 132.

Nutrition, 72.

Ocelli, minute eyes, 28.
(Esophagus, the gullet, 22, 75.
Olfactory, pertaining to the sense of

smell, '21, 36.
Omnivora, feeding upon all kinds of

food, 83.

Oolitic formation, 186.
Operculum, a cover for the aperture

of a shell.
Opliidians, animals of the serpent

kind, xvi.
Optic nerves, 24.
Orbits, 24.
Orders, xiv.
Organism, 7, 13.
Organized bodies, general properties

of, 11 ; elementary structure, 12.
Ornithichuites, 197.
Orthoceras fusiforme, 193.
Osseous tissue, 15.
Otolites, little bones in the ears of

mollusks and Crustacea, 35.
Ovary, the organ in which eggs

originate, 104.
Oviduct, the passage through which

the egg is excluded, 105.
Oviparous, producing eggs, 103.
Ovis montana, 160.
Ovo-viviparous, animals which hatch

their eggs within their body, 105.
Ovulation, the production of eggs,

105.

Oxygen, its consumption in respira-
tion, 17, 95.

Pachydermata, thick-skinned ani-
mals, like the elephant, hog, &c.
82 202.

Paleontology, 183.

Paleozoic age, 190, 191.

Paleotherium, 202.

214

INDEX AND GLOSSARY.

Palpation, the exercise of the touch,
40.

Palpi, jointed organs for touch, about
the mouth of insects, 40.

Pancreas, 101.

Papilla, a little pimple, 38.

Paramecia, reproduction of, 126.

Parasitic, living on other objects.

Passerine, birds of the sparrow kind,
168.

Peduncle or Pedicle, a slender stem.

Pelvis, the cavity formed by the hip-
bones, 60.

Pentacrinus, 199 ; metamorphosis
of, 148.

Perception, 43.

Perchers, a class of birds, xvi.

Peristaltic motion, 76.

Petrifactions, 183.

Pigment, a coloring substance, 27.

Pituitary membrane, 37.

Placenta, the organ by which the
embryo of mammals is attached to
the mother, 121.

Placoids, fishes with a rough skin,
like the shark or skate, xvi.

Planaria, its digestive apparatus, 74 ;
an eye of, 29.

Plant-lice. See Aphides.

Plants compared with animals, 16.

Platynotus, 193.

Pleiocene formation, 187.

Plesiosaurus, 197, 200.

Pleurotomaria, 201.

Ploceus Philippinus, nest of, 47.

Plutonic rocks, 182.

Podurella, mode of leaping, 68; em-
bryo of, 1 14 ; egg of, 104 ; repro-
duction of, 125.

Polyps, a small animal fixed at one
end, with numerous flexible feel-
ers at the other, 3, 29.

Prehension, act of grasping, 85.

Primary age, 195.

Primitive stripe, 113.

Progression, 66.

Proligerous, the part of the egg
where the embryo is placed, 111.

Proteus, 177.

Protosaurus, 196.

Protractile, capable of being ex-
tended.

Pterichthys, 194.

Pterocoma pinnata, 199.

Pterodactylus, 198.

Pteropods, mollusks with wing-like
expansions for swimming, xviii.

Pulmonary, relating to the lungs, 90.

Pulmonates, mollusks which breathe

air, xviii.
Pupil, 25.
Pyrula, egg-cases of, 106.

Quadrumanous, four-handed, 168.
Quadruped, animals with four legs,
16.

Radiata, animals whose organs ra-
diate from a centre, 3.

Radius, one of the bones of the arm,
59.

Relation, functions of, 21.

Reproduction, peculiar modes, 125.

Reptiles, number of, 3 ; reign of,
190, 195.

Respiration, 92.

Retractile, that may be drawn back,
60.

Rhizodonts, xvi ; of the trias, 196.

Rhizopods, xix.

Rocks, classification of, 183.

Rodents, quadrupeds with teeth for
gnawing, 83.

Rotifers, jaws of, 79.

Ruminants, quadrupeds which chew
the cud.

Running1, 67.

Rytina Stelleri, 178.

Salenia, 201.

Saliferous formation, 186.

Saliva, 83.

Salivary glands, 100.

Salpa, reproduction of, 128.

Scansores, birds adapted for climb-

inj?, xvi.
Scaphites, 200.
Scapula, 59.
Sclerotic, the principal coat of the

eye, 25.

Scutella, jaws of, 77.
Sea-anemone. See Actinia.
Sea-urcliin, eye of, 29 ; digestive

organs, 74.

Secondary age, 190, 195.
Secretions, 98.
Sedimentary rocks, 183.
Segment, portion of a circle or

sphere.

Sensation, general, 19, 23.
Senses, special, 23.
Serous, watery, 112.
Shark, egg of,' 104.
Shoulder-blade, 58.
Sight, 24.
Silex, ilinty rock.

INDEX AND GLOSSARY.

215

Siliceous, made of flint.

Silk- worm, metamorphosis of, 143.

Silurian rocks, lower, 185 ; upper,
186.

Sinuous, bending in and out, xvii.

Siphonophori, xviii.

Siren, 177.

Skeleton, 51, 53.

Skin, structure of, 99.

Smell, 36.

Species, the common name of a
thing ; constancy of, 43 ; defini-
tion of,

Spinal marrow, 21.

Spondyli, 201.

Sponges not animal, 17.

Spontaneous generation, 140.

Standing, 64.

Stapes, 33.

Star-fish, metamorphoses of, 146 ;
eye of, 26 ; mode of progression,
57; reproduction of parts, 126.

Stigmata, openings in insects for the
admission of air, 92.

Stomach, 73.

Stratified rocks, 183.

Stratum, a layer.

Strobila, 133, 138.

Structure of the earth's crust, 182.

Sturgeon, compared with white-fish,
148.

Suctoria, insects talcing their food by
suction, xvii.

Swimming, 69.

Sylvia sutoria, nest of, 46.

Systole, the contraction of the heart
to force out the blood, 90.

Tape-worm, reproduction of, 140.

Tarsus, the ancle.

Taste, 38.

Teeth, 79.

Temperate faunas, 166.

Temporal, relating to the temples,
79.

Tentacle, the horn-like organs on the
head of mollusks, usually bearing
the eyes, 28.

Terebratula, 198.

Tertiary age, 190, 201.

Tertiary formation, lower, 186 ; up-
per, 187.

Test, the bristle crust covering the
crustaceans, &c. 51.

Teuthideans, the family of cuttle-
fishes, xvii.

Tibia, one of the bones of the leg, 63.

Tissues, 13 ; areolar, 14 ; cartilagi-
nous, 14 ; osseous, 15 ; nervous,
15.

Tongue, 38.

Touch, 39.

Trachea, the windpipe, 93.

Tracheae, the air-tubes of insects, 92.

Trias formation, 186, 196.

Trisfunia, 198.

Trilobites, 9, 193, xvii.

Trocholites ammdnius, 193.

Trophi, organs for feeding, of insects,
crabs, &c.

Tropical faunas, 172.

Trot, 67.

Tubulibranchiates, xvii.

Tunicata, mollusks with a leathery
covering1, 128.

Turrilites, 200.

Tympanum, a drum ; the membrane
separating the internal and exter-
nal ear, 33.

Type, an ideal image. See p.

Ulna one of the bones of the arm,

59.

Ultimate, final.
Univalve, having a single shell, like

the snail, 3.

Vascular, composed of vessels, 99.

Vegetative life, 20 ; layer, 112.

Veins, 88.

Ventricle, a cavity of the heart, 89.

Vermicular, 76.

Vertebra, a joint of the back-bone,
54.

Vertebrate, having a back-bone, 3.

Vertical, in a perpendicular direc-
tion, 24.

Vesicle, a small membranous bag.
13.

Vestibule, a porch ; the entrance to
one of the cavities of the ear, 34.

Vibratile, moving to and fro, 87.

Viscera, 128.

Vitelline membrane, 108.

Vitellus, 108.

Vitreous humor, 26.

Viviparous, producing living youns,
103.

Vocal cords, 41.

Voice, 40.

Voluntary, under control of the will,
19.

Vorticella, reproduction of, 126.

216

INDEX AND GLOSSARY.

Walking, 66.

Warm-blooded animals, 96.

Water-tubes of aquatic animals, 97.

Whale, fans of, 80.

Whales, mode of swimming, 70.

White-fish, development of, 115.

Worms, eye of, 29.

Zoology, its sphere, 1.

Zoophytes, animals of a very low

type, mostly fixed to the ground

of a plant-like form.

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faction. It is the result of several years' reflection and experience in teaching, on the part
of its justly distinguished author ; and if it is not perfectly what we could wish, yet, in the
most important respects, it supplies a want which has been extensively felt. It is, we
think, substantially sound in its fundamental principles ; and being comprehensive and
elementary in its plan, and adapted to the purposes of instruction, it will be gladly adopted
by those who have for a long time been dissatisfied with the existing works of Paley."

2V(e Literary and Theological Review.

MOKAL SCIENCE, ABRIDGED, by the Author, and adapted
to the use of Schools and Academies. Twenty-fifth Thousand. 18mo.
half morocco. Price 50 cents.

"V The attention of Teachers and School Committees, and all interested in the moral
training of youth is invited to this valuable work. It has received the unqualified
approbation of all who have examined it ; and it is believed to be admirably adapted to
exert a wholesome influence on the minds of the young, and lead to the formation of cor-
rect moral principles.

" Dr. Wayland has published an abridgment of his work, for the use of schools. Of
this step we can hardly speak too highly. It is more than time that the study of moral
philosophy should be introduced into all our institutions of education. We are happy to
see the way so auspiciously opened for such an introduction. It has been not merely
abridged, but also re-written. We cannot but regard the labor as well bestowed." — North
American Review.

" We speak that we do know, when we express our high estimate of Dr. Wayland's
ability in teaching Moral Philosophy, whether orally or by the book. Having listened to
his instructions, in this interesting department, we can attest how lofty are the principles,
how exact and severe the argumentation, how appropriate and strong the illustrations
•which characterize his system and enforce it on the mind." — The Christian Witness.

" The work of which this volume is an abridgment, is well known as one of the best and
most complete works on Moral Philosophy extant. The author is well known as one of
the most profound scholars of the age. That the study of Moral Science, a science which
teaches gooi/ness, should be a branch of education, not only in our colleges, but in our
schools and academies, we believe will not be denied. The abridgment of this work
seems to us admirably calculated for the purpose, and we hope it will be extensively
applied to the purposes for which it is intended." — The Mercantile Journal.

" We hail the abridgment as admirably adapted to supply the deficiency which has long
been felt in common school education, — the study of moral obligation. Let the child
early be taught the relations it sustains to man and to its Maker, the first acquainting it
with the duties owed to society, the second with the duties owed to God, and who can
foretell how many a sad and disastrous overthrow of character will be prevented, and how-
elevated and pure will be the sense of integrity and virtue ? " — Evening Gazette.

Valuable Scljool Books.

ELEMENTS OF POLITICAL ECONOMY. By FRANCIS
WAYLAND, D.D., President of Brown University. Fifteenth' Thousand.
12mo. cloth. Price $1.25

" His object has been to write a book, which any one who chooses may understand. lie
has, therefore, labored to express the general principles in the plainest manner possible,
and to illustrate them by cases with which every person is familiar. It has been to the
author a source of regret, that the course of discussion in the following pages, has, una-
voidably, led him over ground which has frequently been the arena of political contro-
versy. In all such cases, he has endeavored to state what seemed to him to be truth,
without fear, favor, or affection. He is conscious to himself of no bias towards any party
whatever, and he thinks that he who will read the whole work, will be convinced that he
has been influenced by none." — Extract from the Preface.

POLITICAL ECONOMY, ABRIDGED, by the Author, and
adapted to the use of Schools and Academies. Seventh Thousand.
ISmo. half morocco. Price 50 cents.

*** The success which has attended the abridgment of " The Elements of Moral
Science " has induced the author to prepare an abridgment of this work. In this case,
as in the other, the work has been wholly re-written, and an attempt has been made to
adapt it to the attainments of youth.

" The original work of the author, on Political Economy, has already been noticed on
onr pages ; and the present abridgment stands in no need of a recommendation from us.
We may be permitted, however, to say, that both the rising and risen generations are
deeply indebted to Dr. Wayland, for the skill and power he has put forth to bring a highly
important subject distinctly before them, within such narrow limits. Though ' abridged
for the use of academies,' it deserves to be introduced into every private family, and to be
studied by every man who has an interest in the wealth and prosperity of his country. It
is a subject little understood, even practically, by thousands, and still less understood
theoretically. It is to be hoped, this will form a class-book, and be faithfully studied in
our academies ; and that it will find its way into every family library ; not there to be
shut up unread, but to afford rich material for thought and discussfon in the family
circle. It is fitted to enlarge the mind, to purify the judgment, to correct erroneous
popular impressions, and assist every man in forming opinions of public measures,
which will abide the test of time and experience." — Boston Recorder.

" An abridgment of this clear, common sense work, designed for the use of academies
is just published. We rejoice to see such treatises spreading amon°; the people ; and we
urge all who would be intelligent freemen, to read them." — New York Transcript.

" We can say, with safety, that the topics are well selected and arranged ; that the
author's name is a guarantee for more than usual excellence. We wish it an extensive
circulation." — New York Observer.

" It is well adapted to high schools, and embraces the soundest system of republican
political economy of any treatise extant." — Daily Advocate.

THOUGHTS on the present Collegiate System in the United States.
By FRANCIS WAYLAND, D.D. Price 50 cents.

" These Thoughts come from a source entitled to a very respectful attention ; and as the
author goes over the whole ground of collegiate education, criticising freely all the arrange-
ments in every department and in all their bearings, the book is very full of matter. We
hope it will prove the beginning of a thorough discussion."

PALEY'S NATURAL THEOLOGY. Illustrated by forty plates,
and Selections from the notes of Dr. Paxton, with additional Notes,
original and selected, for this edition ; with a vocabulary of Scientific
Terms. Edited by JOHN WARE, M.D. 12mo. sheep. Price $1.25.

" The work before us is one which deserves rather to be studied than merely read.
Indeed, without diligent attention and study, neither the excellences of it can be fully dis-
covered, nor its advantages realized. It is, therefore, gratifying to find it introduced, as a
text-book, into the colleges and literary institutions of our country. The edition before us
is superior to any we have seen, and, we believe, superior to any that has yet been pub-
lished." — Spirit of the Pilgrims.

"Perhaps no one of our author's works gives greater satisfaction to all classes of readers,
the young and the old, the ignorant and the enlightened. Indeed, we recollect no book in
which the arguments for the existence and attributes of the Supreme Being, to be drawn
from his works are exhibited in a manner more attractive and more convincing."

Christian Examiner.

Valuable Bdjool Books.

CLASSICAL STUDIES. Essays on Ancient Literature and Art.
With the Biography and Correspondence of eminent Philologists. By
BARNAS SEARS, President Newton Theol. Institution, B. B. EDWARDS,
Prof. Andover Theol. Seminary, and C. C. FELTON, Professor Harvard
University. 12rno. cloth. Price $1.25.

" This book will do good in our colleges. Every student will want a copy, and many
will be stimulated by its perusal to a more vigorous ajid enthusiastic pursuit of that higher
and more solid learning which alone deserves to be called ' classical.' The recent tenden-
cies have been to the neglect of this, and we rejoice in this timely effort of minds so well
qualified for such a work." — Reflector.

" The object of the accomplished gentlemen who have engaged in its preparation has
been, to foster and extend among educated men, in this country, the already growing inter-
est in classical studies. The design is a noble and generous one, and has been executed
with a taste and good sense, to do honor both to the writers and the publishers. The book
is one which deserves a place in the library of every educated man. To those now
engaged in classical study it cannot fail to be highly useful, while to the more advanced
scholar it would open new sources of interest and delight in the unforgotten pursuits of
his earlier days." — Providence Journal.

THE CICERONIAN; Or the Prussian Method of Teaching the
Latin Language. Adapted to the use of American Schools, by B. SEARS.
18mo. half morocco. Price 50 cents.

From the Professors of Harvard University.

" We beg leave to observe, that we consider this book a very valuable addition to our
stock of elementary works. Its great merit is, that it renders the elementary instruction in
Latin less mechanical, by constantly calling the reasoning power of the pupil into action,
and gives, from the beginning, a deeper insight into the very nature, principles, and laws
not only of the Latin language, but of language in general. If the book required any
other recommendation besides that of being the work of so thorough and experienced a
scholar as Dr. Sears, it would be this, that the system illustrated in it is not a mere theory,
but has been practically tested by many able instructors in Germany. We wish that the
eame trial may be made here. Very respectfully yours, CHARLES BECK,

Cambridge, Oct. 2, 1844. C C" FELTON.

From S. H. Taylor, Principal of Phillips' Academy, Andover.

' I have examined, with much pleasure and profit, the ' Ciceronian,' prepared by
Dr. Sears. It is admirably adapted to make thorough teachers and thorough pupils. It
requires of the teacher a precise and intimate acquaintance with the minutiae of the Latin
tongue, and necessarily induces in the pupil habits of close thought and nice discrimina-
tion. The plan of the work is excellent, as it constantly calls the attention of the pupil to
the peculiar construction and idioms of the language ; and, by a system of constant
reviews, keeps the attention upon them till they are permanently fixed. The pupil who
shall go through this book in the manner pointed out in the plan of instruction, will
know more of the Latin than most do who have read volumes. e TT rp,. „„

«• Andover, Oct. 3, 1844.

M E M 0 R I A TECHNICA; Or, the Art of Abbreviating those Studies
which give the greatest Labor to the Memory ; including Numbers,
Historical Dates, Geography, Astronomy, Gravities, &c. ; also Eules for
Memorizing Technicalities, Nomenclatures, Proper Names, Prose, Poetry,
and Topics in general. Embracing all the available Rules found in
Mnemonics or Mnemotechny of Ancient and Modern Times. To which
is added a perpetual Almanac for Two Thousand Years of Past Time and
Time to Come. By L. D. JOHNSON. Third Edition, revised and improved.
Octavo, cloth back. Price 50 cents.

" This system of Mnemotechny, differing considerably from the one introduced by Prof.
Gouraud, is designed to furnish all the rules for aiding the memory without lessening
mental culture, which can be made available during a course of elementary study. The
illustrations may be easily comprehended by any person of ordinary mental capacity;
and the application of the principles upon which the system is based, must necessarily
furnish an agreeable and useful exercise to the mind." — New York Teachers' Advocate.

"We feel no hesitation in recommending this work to the deliberate attention of teach-
ers, and the guardians of youth. We learn that it is received into several schools in
Boston, and used as an auxiliary help to the studies now pursued by the pupils."

Boston Conner.

" The ' Memoria Technica' is now studied in some of onr best schools ; and the system
taught iii it appears to be much approved by those who have made trial of it."

Evening Traveller.

GOULD, KENDALL AND LINCOLN'S PUBLICATIONS.

THE FOUR GOSPELS, WITH NOTES. Chiefly Explanatory ; in-
tended principally for Sabbath School Teachers and Bible Classes, and
as an aid to Family Instruction. By HENRY J. RIPLEY, Xewton Theol.
Institution. Seventh Edition. Price $1.25.

*** This work should be in the hands of every student of the Bible, especially every
Sabbath School and Bible Class teacher. It is prepared with special reference to this class
of persons, and contains a mass of just the kind of information wanted.

" The undersigned, having examined Professor Ripley's Notes on the Gospels, can
recommend them with confidence to all who need such helps in the study of the sacred
Scriptures. Those passages which all can understand are lett ' without note or comment,'
and the principal labor is devoted to the explanation of such parts as need to be explained
and rescued from the perversions of errorists, both the ignorant and the learned. The
practical suggestions at the close of each chapter, are not the least valuable portion of the
work. Most cordially, for the sake of truth and righteousness, do we wish for these Notes
a wide circulation.

BARON STOW, R. H. NEALE, R, TCRNBULL,

DANIEL SHARP, J. W. PARKER, N. COLTER.
WM. HAGUE, R, "W. CCSHMAN,

THE ACTS OF THE APOSTLES, WITH NOTES. Chiefly Ex-
planatory. Designed for Teachers in Sabbath Schools and Bible Classes,
and as an Aid to Family Instruction. By Prof. HENRY J. RIPLEY.
Price 75 cents.

" The external appearance of this book, — the binding and the printed page, — 'it is
a pleasant thing for the eyes to behold.' On examining the contents, we are favorably
impressed, first, by the wonderful perspicuity, simplicity, and comprehensiveness of th'e
author's style ; secondly, by the completeness and systematic arrangement of the work, in
all its parts, the ' remarks ' on each paragraph being carefully separated from the exposi-
tion ; thirdly, by the correct theology, solid instruction, and consistent explanations of
difficult passages. The work cannot fail to be received with favor. These Notes are much
more full than the Notes on the Gospels, by the same author. A beautiful map accompanies
them." — Christian Reflector, Boston.

CRUDEN'S CONDENSED CONCORDANCE. A Complete Con-
cordance to the Holy Scriptures ; by ALEXANDER CRUDEN, M.A. A
New and Condensed Edition, with 'an Introduction; by Rev. DAVID
KING, LL.D. Fifth Thousand. Price in Boards, 81.25 ; Sheep, $1.50.

V'This edition is printed from English plates, and is a full and fair copy of all
that is valuable in Cruden as a Concordance. The principal variation from the larger book
consists in the exclusion of the Bible Dictionary, which has long been an incumbrance,
and the accuracy and value of which have been depreciated by works of later date, contain-
ing recent discoveries, facts, and opinions, unknown to Cruden. The condensation of
the quotations of Scripture, arranged under their most obvious heads, while it diminishes
the bulk of the work, greatly facilitates the finding of any required passage.

" Those who have been acquainted with the various works of this kind now in use,
well know that Cruden's Concordance far excels all others. Yet we have in this edition of
Cruden, the best ma.de better. That is, the present is better adapted to the purposes of a
Concordance, by the erasure of superfluous references, the omission of unnecessary expla-
nations, and the contraction of quotations, &c. ; it is better as a manual, and is better
adapted by its price to the means of many who need and ought to possess such a work,
than the former larger and expensive edition." — Boston Recorder.

" The new, condensed, and cheap work prepared from the voluminous and costly one of
Cruden, opportunely fills a chasm in our Biblical literature. The work has been examined
critically by several ministers, and others, and pronounced complete and accurate."

£d}itist Record, Phila.

This is the very work of which we have long felt the need. We obtained a copy of
the English edition some months since, and wished some one would publish it ; and we
are much pleased that its enterprising publishers can now furnish the student of the Bible
with a work which he so much needs at so cheap a rate." — Advent Herald, Boston.

" We cannot see but it is, in all points, as valuable a book of reference, for ministers and
Bible students, as the larger edition." — Christian Reflector, Boston.

" The present edition, in being relieved of some things which contributed to render all
former ones unnecessarily cumbrous, without adding to the substantial value of the work,
becomes an exceedingly cheap book." — Albany Argus.

GOliLU, KL^DALL A^'D LI-NCOLS t> PUBLICATIONS.

CHAMBERS'S CYCLOPAEDIA OF ENGLISH LITERATURE;

A Selection of the Choicest Productions of English Authors, from the
earliest to the present time ; Connected by a Critical and Biograph-
ical History. Edited by ROBERT CHAMBERS, assisted by ROBERT
CARRUTHEKS, and other eminent Gentlemen. Complete in two im-
perial octavo volumes, of more than fourteen hundred pages of double
column letter press ; and upwards of 300 elegant illustrations. Price,
in cloth, $5,00.

V The Publishers of the AMERICAN Edition of this valuable work desire to state, that,
besides the numerous pictorial illustrations in the English Edition, they have greatly en-
riched the work by the addition of fine steel and mezzotint engravings of the heads of Shaks-
peare, Addison, Byron ; a full length portrait of Dr. Johnson, and a beautiful scenic repre-
sentation of Oliver Goldsmith and Dr. Johnson. These important and elegant additions
together with superior paper and binding, must give this a decided preference over all
other editions.

" We hail with peculiar pleasure the appearance of this work, and more especially its
republication in this country at a price which places it within the reach of a great number
of readers. We have been inundated by a stream of cheap reprints, tending to corrupt the
morals and vitiate the taste of our community, and we are pleased that the publishers have
still sufficient faith in the purity of both, to induce them to incur the large outlay which
the production of the work before us must have occasioned, and for which they can expect
to be remunerated only by a very extensive sale."

" The selections given by Mr. Chambers from the works of the early English writers are
copious, and judiciously made. ***** We shall conclude as we commenced, with ex-
pressing a hope that the publication which has called forth our remarks will exert an influ-
ence in directing the attention of the public to the literature of our forefathers."

North American Review.

CHAMBERS'S MISCELLANY of Useful and Entertaining Knowledge,
with elegant illustrative engravings. Edited by WILLIAM CHAMBERS.
Price 25 cents per number, to be completed in ten Elegant volumes.

*** The design of the MISCELLANY is to supply the increasing demand for useful, in-
structive, and entertaining reading, and to bring all the aids of literature to bear on the cul-
tivation of the fcelimjs and imdcrstdndiity of the people — to impress correct views on impor-
tant moral and social questions — suppress every species of strife and savagery — cheer the
lagging and desponding by the relation of tales drawn from the imagination of popular
writers — rouse the fancy by descriptions of interesting foreign scenes — give a zest to
every-day occupations by ballad and lyrical poetry — in short, to furnish an unobtrusive
friend and guide, a lively fireside companion, as far as that object can be attained through
the instrumentality of books.

CHAMBERS'S LIBRARY FOR YOUNG PEOPLE. A series of small
books, elegantly illuminated. Edited by WILLIAM CHAMBERS. Each
volume forms a" complete work, embellished with a fine steel engraving,
and is sold separately. Price 37 J cents.

ORLANDINO: A Story of Self-Denial. By MARIA EDGEWORTH.
THE LITTLE ROBINSON: And other Tales.
UNCLE SAM'S MONEY BOX. By Mrs. S. C. HALL.
TRUTH AND TRUST. Jervis Ryland — Victor and Lisette.
JACOPO : Tales by Miss EDGEWORTH and others.
POEMS. By various Authors, for the young.

The aim of this series is to make the young reader better and happier ; to this end, th'
selection of subjects will be designed to influence the heart and feelings.

0^= Other volumes are in preparation.

Valuable Sdjoot Books.

BLAKE'S FIRST BOOK IN ASTRONOMY. Designed for
the Use of Common Schools. By J. L. BLAKK, D.D. Illustrated by
Steel Plate Engravings. 8vo. cloth back. Price 50 cents.

From E. Hinckley, Professor of Mathematics in Maryland University.

" I am much indebted to you for a copy of the First Book in Astronomy. It is a work
of utility and merit, tar superior to auy other which I have seen. The author has selected
his topics with great judgment, — arranged them in admirable order, — exhibited them in
a style and manner at once tasteful and philosophical. Nothing seems wanting, —nothing
redundant. It is truly a very beautiful and attractive book, calculated to aflbrd both
pleasure and profit to all who "may enjoy the advantage of perusing it."

From B. Field, Principal of the Hancock School, Boston.

" I know of no other work on Astronomy so well calculated to interest and instruct
young learners in this sublime science."

From James F. Gould, A.M., Principal of the High School for Young Ladies,

Baltimore, JtlJ.

"I shall introduce your First Book in Astronomy into my Academy in September,
consider it decidedly superior to any elementary work of the kind I have ever seen."

From Isaac Foster, Instructor of Youth, Portland.

"I have examined Blake's First Book in Astronomy, and am much pleased with it. A
very happy selection of topics is presented in a manner which cannot fail to interest the
learner, while the questions will assist him materially in fixing in the memory what ought
to be retained. It leaves the most intricate parts of the subject for those who are able to
master them, and brings before the young pupil only what can be made intelligible and
interesting to him."

" The illustrations, both pictorial and verbal, are admirably intelligible ; and the defini-
tions are such as to be easily comprehended by juvenile scholars. The author has inter-
woven with his scientific instructions much interesting historical information, and con-
trived to dress his philosophy in a garb truly attractive. — -V. i*. Daily Ei cnunj Journal.

" We are free to say. that it is, in our opinion, decidedly the best work we have any
knowledge of, on the sublime and interesting subject of Astronomy. The engravings are
executed in a superior style, and the mechanical appearance of the book is extremely
prepossessing. The knowledge imparted is in language at once chaste, elegant, and
simple — adapted to the comprehension of those for whom it was designed. The subject
matter is selected with great judgment, and evinces uncommon industry and research.
\Ve earnestly hope that parents and teachers will examine and judge for themselves, as
we feel confident they will coincide with us in opinion. We only hope the circulation of
the work will be commensurate with its merits." — Boston Evening Gazette.

" The book now before us contains forty-two short lessons, with a few additional ones,
which are appended in the form of problems, with a design to exercise the young learner
in finding out the latitude and longitude on the terrestrial globe. We do not hesitate to
recommend it to the notice of the superintending committees, teachers, and pupils of our
public schools. The definitions in the first part of the volume are given in brief and clear
language, adapted to the understanding of beginners."— State Herald, Portsmouth, X. H.

BLAKE'S NATURAL PHILOSOPHY. Being Conversations on
Philosophy, with the addition of Explanatory Note?, Questions for Exami-
nation, and a Dictionary of Philosophical Terms. With twenty-eight steel
Engravings. By J. L. 'BLAKE, D.D. 12mo. sheep. Price 67 cents.

*** Perhaps no work has contributed so much as this to excite a fondness for the study
of Natural Philosophy in youthful minds. The familiar comparisons, with which it
abounds, awaken interest, and rivet the attention of the pupil.

From Rev. J. Adams, President of Charleston College, S. C.

"I have
Natural Philos
additions to
acquainted. I shall recommend it wherever I have an opportunity.'

"We avail ourselves of the opportunity furnished us by the publication of a new edition
of this deservedly popular work, to recommend it. not only to those instructors who may
not already have" adopted it, but also generally to all readers who are desirous of obtaining
informatio'n on the subjects on which it treats. By Questions arranged at the bottom of
the pages, in which the collateral facts are arranged, he directs the attention of the learner
to the principal topics. Mr. Blake has also added many Notes, which illustrate the pas-
sages to which they are appended, and the Dictionaiy of Philosophical Terms is a useful
addition,"— U. S. Literary Gazette.

Valuable Sdjool 33ook0.

THE YOUNG LADIES' CLASS BOOK. A Selection of
Lessons for Reading hi Prose and Verse. By E. BAILEY. A.M.,
late Principal of the Noting Ladies' High School, Boston. Stereotyped
Edition. 12mo. sheep. Price 83X cents.

From the Principals of the Public Schools for Females, Boston.

" GENTLEMEN : — We have examined the Young Ladies' Class Book with interest and
pleasure ; with interest, because we have felt the want of a Reading Book expressly de-
signed for the use of females; and with pleasure, because we have found it well adapted
to supply the dericiency. In the selections for a Reader designed for boys, the eloquence
of the bar, the pulpit, and the forum may be laid under heavy contribution ; but such
selections, we conceive, are out of place in a book designed for females. We have been
pleased, therefore, to observe, that in the Young Ladies' Class Book such pieces are rare.
The high-toned morality, the freedom from sectarianism, the taste, richness, and adapta-
tion of the selections, added to the neatness of its external appearance, must commend it to
all; while the practical teacher will not fail to observe that diversity of style, together with
those peculiar points, the want of which, few, who have not felt, know how to supply.

Respectfully yours, BAKNUM FIELD, ABRAHAM ANDREWS,

R. G. PAKKEE, CHARLES Fox"

From the Principal of the Mount Vernon School, Boston.

"I have examined with much interest the Young Ladies' Class Book, by Mr. Bailey
and have been very highly pleased with its contents. It is my intention to introduce it
into my own school ; as I regard it as not only remarkably well fitted to answer its particu-
lar object as a book of exercises in the art of elocution, but as calculated to have an influ-
ence upon the character and conduct, which will be in every respect favorable.

JACOB ABBOTT."

"We were never so struck with the importance of having reading books for female
schools, adapted particularly to that express purpose, as while looking over the pages of
this selection. The eminent success of the compiler in teaching this branch, to which we
can personally bear testimony, is sufficient evidence of the character of the work, consid-
ered as a selection of lessons in elocution ; they are, in general, admirably adapted to
cultivate the amiable and gentle traits of the female character, as well as to elevate and
improve the mind." — Ann'ils of Education.

" The reading books prepared for academic use, are often unsuitable for females. We
are glad, therefore, to perceive that an attempt has been made to supply the deficiency ; and
we believe that the task has been faithfully and successfully accomplished. The selections
are judicious and chaste ; and so far as they have any moral bearing, appear to be unex-
ceptionable." — Education Reporter.

ROMAN ANTIQUITIES AND ANCIENT MYTHOLOGY.

By C. K. DILLAWAY, A.M., late Principal in the Boston Latin School.
With Engravings. Eighth EcL, improved. 12mo. half mor. Price 67 cts.

From E. Bailey, Principal of the Young Ladies' High School, Boston.

" Having used Dillaicay's Roman Antiquities and Ancient Mythology in my school for
several years, I commend it to teachers with great confidence, as a valuable text-book on,
those interesting branches of education. E. BAILEY.'

" The want of a cheap volume, embracing a succinct account of ancient customs,
together with a view of classical mythology, has long been felt. To the student of a lan-
guage, some knowledge of the manners, habits, and religious feelings of the people whose
language is studied is indispensably requisite. This knowledge is seldom to be obtained
without tedious research or laborious investigation. Mr. Dillaway's book seems to have
been prepared with special reference to the wants of those who are just entering upon a
classical career; and we deem it but a simple act of justice to say, that it supplies the
want, which, as we have before said, has long been felt. In a small duodecimo, of about
one hundred and fifty pages, he concentrates the most valuable and interesting particulars
relating to Roman antiquity ; together with as full an account of heathen mythology as is
generally needed in our highest seminaries. A peculiar merit of this compilation, and
one which will gain it admission into our highly respectable female seminaries, is the total
absence of all allusion, even the most remote, to the disgusting obscenities of ancient
mythology; while, at the same time, nothing is omitted which a pure mind would feel
interested to know. We recommend the book as a valuable addition to the treatises in
our schools and academies." — Education Reporter, Boston.

"We well remember, in the days of our pupilage, how unpopular as a study was tho
volume of Roman Antiquities introduced in the academic course. It wearied on account
of its prolixity, filling a thick octavo, and was the prescribed task each afternoon for a
long three months. It was reserved for one of our Boston instructors to apply the con-
densing apparatus to this mass of crudities, and so to modernize the antiquities of the old
Romans, as to make a befitting abridgment for schools of the first order. Mr. Dillaway has
presented such a compilation as must be interesting to lads, and become popular as a text-
book. Historical facts are stated with great simplicity and clearness ; the most important
points ore seised upon, while trifling peculiarities are passed unnoticed."— Am. Traveller.

GOULD, KENDALL AND LINCOLN a PUBLICATIONS.

THE CHRISTIAN'S DAI LY TREASURY. A Religious Exercise for
every day in the Year. By Rev. EKENEZER TEMPLE. Price $1.00

=%:* This work is strictly evangelical, and presents with great distinctness the peculiar
points of orthodoxy. The texts are happily chosen, and all the thoughts suggested by
the author are interesting and profitable. The skeletons are generally of the textual
character, very neat, comprehensive, and each of them contains matter enough for a
sermon. There is a great variety of beautiful gems scattered through it, both original
and selected,

This work might appropriately be called a guide to meditation. It consists of a subject
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THE APOSTOLICAL AND PRIMITIVE CHURCH; Popular in
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an introductory essay, by Dr. AUGUSTUS NEANDER, of Berlin. Second
Edition. Price $1.25.

The Publishers have been favored with many highly commendatory notices of this
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Seminaries.

From the Professors in Andover Theological Seminary.

" The undersigned are pleased to hear that you are soon to publish a new edition of the
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public." LEONARD WOODS, BELA B. EDWARDS,

RALPH EMERSON, EDWARD A. PARK.

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THE CHURCH MEMBER'S MANUAL Of Ecclesiastical Principles,
Doctrines, and Discipline ; presenting a Systematic View of the Structure,
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Scriptures ; by WM. CROWELL. With an Introductory Essay, by HENRY
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We cordially concur in the above recommendation. S. H. Cone, Elisha Tucker, W. W.
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" This very complete Manual of Church Polity is all that could be desired in this depart-
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CLASSICAL STUDIES: Essays on Ancient Literature and Art.
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GESENIUS'S HEBREW GRAMMAR. Translated from the Eleventh
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uuremitted, unwearied, energetic efforts, — what are we to expect from such a man as
Gesenius? Has he talent, judgment, tact, as a philologist? Read his work on Isaiah ;
compare his Hebrew Grammar with the other grammars of the Hebrew which Germany has
yet produced ; read and compare any twenty, or even ten articles on any of the difficult and
important words in the Hebrew with the same in Buxtorff, Cocceius, Stockins, Eichhorn's
Sinioui, Winer, even (Parkhurst, I cannot once name), and then say whether Gesenius, as
a Hebrew philologer, has talents, tact, and judgment. Nothing but rival feelings, or preju-
dice, or antipathy to his theological sentiments, can prevent a unity of answer."

LIFE OF GODFREY WILLIAM VON LIEBNITZ. On the basis
of the German Work of Dr. G. E. Guhrauer. By JOHN M. MACK.IE.
Price 75 cents.

" The peculiar relation which Liebnitz sustained during his life to Locke and Newton
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" There is perhaps no case on record of a single man who has so gone the rounds of human
knowledge as did Liebuitz : he was not a recluse, like Spinoza and Kant, but went from
capital to capital, and associated with kings and premiers. All branches of thought were
interesting to him, and he seems in pursuing all to have been actuated not by ambition,
but by a sincere a desire to promote the knowledge and welfare of mankind. —Ohrist. World.

LIFE OF ROGER Wl L LI A MS, The Founder of the State of Rhode
Island. By WM. GAMMELL, Professor of Rhetoric in Brown University.
With a likeness. Price 75 cents.

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private citizen, and not as a public journalist. Its mechanical execution is in the usually neat
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" This life has many virtues — brevity, simplicity, fairness. Though written by a Rhode
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THE MISSIONARY ENTERPRISE; A Collection of Discourses

on Christian Missions, by American Authors. Edited by BAKON
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" You see the high talent of the American church. "We venture the assertion, that no
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THE GREAT COMMISSION; Or, the Christian Church constituted
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THE KAREN APOSTLE; Or, Memoir of Ko THAH-BYU, the first
Karen convert, with notices concerning his Nation. WTith maps and
plates. By the Rev. FRANCIS MASON, ^Missionary. American Edition.
Edited by Prof. H. J. RIPLEY, of Newton Theol. Institution. Fifth Thou-
sand. Price 25 cents.

*#* " This is a work of thrilling interest, containing the history of a remarkable man, and
giving, also, much information respecting the Karen Mission, heretofore unknown in this
country. It must be sought for, and read with avidity by those interested in this most in-
teresting mission. It gives an account, which must be attractive, from its novelty, of a
people that have been but little known and visited by missionaries, till within a few years*
The baptism of Ko Thah-Byu, in 1828, was the beginning of the mission, and at the end of
these twelve years, twelve hundred and seventy Karens are officially reported as members
of the churches, in good standing. The mission has been carried on pre-eminently by the
Karens themselves, and there is no doubt, from much touching evidence contained in this
volume, that they are a people peculiarly susceptible to religious impressions. The account
of Mr. Mason must be interesting to every one.

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of

MEMOIR OF ANN H. JUDSON, late Missionary to Burmali. By Rev.
JAMES D. KNOWLES. 12mo. Edition, price 85 cents. ISmo., price 58 cts.

" We are particularly gratified to perceive a new edition of the Memoirs of Mrs. Judson.
She was an honor to our country — one of the most noble-spirited of her sex. It cannot,
therefore, be surprising, that so many editions, and so many thousand copies of her life and
adventures have been sold. The name — the long career of suffering — the self-sacriticing
spirit of the retired country-girl, have spread over the whole world ; and the heroism of her
apostleship and almost martyrdom, stands out a living and heavenly beacon-tire, amid the
dark midnight of ages, and human history and exploits. She was the first woman who
resolved to become a missionary to heathen countries." — American Traveller.

" This is one of the most interesting pieces of female biography which has ever come un-
der our notice. No quotation, which our limits allow, would do justice to the facts, and we
must, therefore, refer our readers to the volume itself. It ought to be immediately added to
every family library." — London Miscellany.

MEMOIR OF GEORGE DANA BOARDMAN, Late Missionary to
Burmah, containing much intelligence relative to the Burman Mission.
By Rev. ALONZO KING. A new Edition. With an Introductory Essay,
by a distinguished Clergyman. Embellished with a Likeness ; a
beautiful Vignette, representing the baptismal scene just before his
death ; and a drawing of his tomb, taken by Rev. H. MALCOM, D.D.
Price 75 cents.

" One of the brightest luminaries of Burmah is extinguished, —dear brother Boardman
is gone to his eternal rest. He fell gloriously at the head of his troops — in the arms of vic-
tory, — thirty-eight wild Karens having been brought into the camp of king Jesus since the
beginning of the year, besides the thirty-two that were brought in during the two preceding
years. Disabled by wounds, he was obliged, through the whole of the last expedition, to be
carried on a litter ; but his presence was a host, and the Holy Spirit accompanied his
dying whispers with almighty influence." REV. DR. JUDSOX.

': No one can read the Memoir of Boardman, -without feeling that the religion of Christ is
suited to purify the affections, exalt the purposes, and give energy to the character. Mr.
Boardman was a man of rare excellence, and his biographer, by a just exhibition of that
excellence, has rendered an important service, not only to the cause of Christian missions)
but to the interests of personal godliness." BAKON STOW.

MEMOIR OF MRS. HENRIETTA SHUCK, The First American
Female Missionary to China. By Rev. J. B. JETER. Fourth thousand.
Price 50 cents.

" We have seldom taken into our hands a more beautiful book than this, and we have
no small pleasure in knowing the degree of perfection attained in this country in the arts
of printing and book-binding, as seen in its appearance. The style of the author is sedate
and perspicuous, such as we might expect from his known piety and learning, his attach-
ment to missions, and the amiable lady whose memory he embalms. The book will be ex-
tensively read and eminently useful, and thus the ends sought by the author will be hap-
pily secured. We think we are not mistaken in this opinion ; for those who taste the
effect of early education upon the expansion of regenerated convictions of duly and happi-
ness, who are charmed with youthful, heroic self-consecration upon the altar of God, for the
welfare of man, and who are interested in those struggles of mind which lead men to shut
their eyes and ears to the importunate pleadings of filial affection — those who are interested
in China, that large opening field for the glorious conquests of divine truth, who are inter-
ested in the government a?id habits, social and business-like, of the people of this empire —
all such will be interested in this Memoir. To them and to the friends of missions generally,
the book is commended, as worth}* of an attentive perusal." — The Family Viaiter, Boston.

MEMOIR OF REV. WILLIAM G. CROCKER, Late Missionary in
West Africa, among the Bassas, Including a History of the Mission. By
R. B. MEDBERY. Price 62£ cents.

" This interesting work will he found to contain much valuable information in relation to
the present state and prospects of Africa, and the success of Missions in that interesting
country, which has just taken a stand among the nations of the earth, and, it is to be hoped,
may successfully wield its new powers for the ultimate good of the whole continent. The
present work is commended to the attention of every lover of the liberties of man.

" Our acquaintance with the excellent brother, who is the subject of this Memoir, will be
long ar>d fondly cherished. This volume, prepared by a latf/t, of true taste and talent, and
of a kindred spirit, while it is but a just tribute to his worth, will, we doubt not, furnish
lessons of humble and practical piety, and will give such facts relative to the mission to
which he devoted his life, as to render it worthy a distinguished place among the religious
and missionary biography which has so much enriched the family of God."— Ch. Watchman.

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brightest that are found in the world." — Jv. Y. Observer.

THE ATTRACTIONS OF HEAVEN. Edited by Eev. H. A.
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LYRIC GEMS. A Collection of Original and Select Sacred Poetry.
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HOW TO BE A LADY? A Book for Girls, containing useful hints on
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bred, intelligent, refined, and good ; and then they will be real ladies, in the highest sense."

Preface.

" We notice these two books together, not merely because they are by the same author,
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They are both full of wholesome and judicious counsels, which are well fitted to preserve
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early youth, from eight or ten to fifteen or sixteen years of age." — Preface.

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ANECDOTES FOR BOYS? Entertaining Anecdotes and Narratives,
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We cordially commend these volumes to all parents and children." — Christian Alliance.

CHRISTIANITY DEMONSTRATED in four distinct and indepen-
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The object of the writer has been to classify and condense the evidence, that the whole
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" It seems to us a very successful specimen of the synthetical mode of reasoning. It puts
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THE GREAT COMMISSION ; Or, the Christian Church constituted
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comforts of many a happy fireside. The reader will rise from ea'ch chapter, not able, per-
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MAMMON I Or, Covetousness, the Sin of the Christian Church. A Prize
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CHAMBERS'S MISCELLANY

OF USEFUL AND ENTERTAINING KNOWLEDGE.

Edited by "WILLIAM CHAMBERS.
With Elegant Illustrative Engravings. Price, 25 cts. per ATo.

GOULD, KENDALL & LINCOLN are happy to announce that they have
completed arrangements with the Messrs. Chambers, of Edinburgh, for the
re-publication, in semi-monthly numbers, of CHAMBERS'S MISCELLANY.
The first number will be issued in July, and continued at regular intervals
until the work is completed.

The design of the MISCELLANY is to supply the increasing demand for
useful, instructive, and entertaining reading, and to bring all the aids of
literature to bear on the cultivation of the feelings and understandings of
the people — to impress correct views on important moral and social ques-
tions— suppress every species of strife and savagery — cheer the lagging
and desponding, by the relation of tales drawn from the imagination of
popular writers — rouse the fancy, by descriptions of interesting foreign
scenes — give a zest to every-day occupations, by ballad and lyrical po-
etry— in short, to furnish an unobtrusive friend and guide, a lively fireside
companion, as far as that object can be attained through the instrumentality
of books.

The universally acknowledged merits of the CYCLOPAEDIA OF ENGLISH
LITERATURE, by the Chambers', connected with its rapid sale, and the
unbounded commendation bestowed by the press, give the publishers full
confidence in the real value and entire success of the present work.

The subjoined table of contents of the first two volumes will give the best
idea of the comprehensive character and diversified contents of this work :

VOL. I.

No. 1. Life of Louis Philippe.
Tale of Norfolk Island.
Story of Colbert.
The Employer and Employed.
Time Enough. By Mrs. S. 0. Hall.
Manual for Infant Management.
Piccioli, or the Prison Flower.
Life in the Bash. By a Lady.

No. 2. William Tell and Switzerland.

The Two Beggar Boys. A Tale.
Poems of the Domestic Affections.
Life of Grace Darling, &c.
Story of Maurice and Genevieve.
Religious Imposters.
Anecdotes of Dogs.

No. 3. La Rochejaquelein and the War in

La Vendee.

Journal of a Poor Yicar.
Romance of Geology.
History of the Slave Trade.
Walter Ruysdael. the Watchmaker.
Chevy-Chase, and the Beggar's
Daughter of Bethnal-Green.

VOL. n.

No. 4. Life of Nelson.

The Temperance Movement.
Story of Peter Williamson.
Joan of Arc, Maid of Orleans.
Annals of the Poor — Female In-
dustry and Intrepidity.
Slavery in America.

No. 5. A Visit to Vesuvius, Pompeii, and
Herculaneum.

Story of Baptiste Lulli.

Select Poems of Kindness to Ani-
mals.

Wallace and Bruce.

Cases of Circumstantial Evidence.

Story of Richard Falconer, &c.

No. 6. The Goldmaker's Village.

The Last Earl of Derwentwater.
The Heroine of Siberia.
Domestic Flower-Culture.
Insurrections in Lyons.
The Hermit of Warkworth, and
Other Ballads.

Each number will form a complete work, and every third number will be furnished
with a title page and table of contents, thus forming a beautifully illustrated VOLUME
of over 500 pages, of useful and entertaining reading, adapted to every class of readers.
The whole to be completed in THIRTY NUMBERS, forming TEN ELEGANT VOLUMES.

d?" This work can be sent by mail to any part of the country. A direct remittance
to the publishers of six DOLLARS will pay for the entire work. This liberal discount
for advance pay will nearly cover the cost of postage on the work. Those wishing for
one or more sample numbers can remit accordingly.

Qp=" Booksellers and Agents supplied on the most liberal terms.

CHAMBERS'S

CYCLOPEDIA OF ENGLISH LITERATURE:

A SELECTION OF THE CHOICEST PRODUCTIONS

OF ENGLISH AUTHORS, FROM THE EARLIEST TO THE PRESENT TBtE.
CONNECTED BY A CRITICAL AND BIOGRAPHICAL HISTORY.

EDITED BY ROBERT CHAMBERS,

ASSISTED BY EOBEET CAREUTHEBS AND OTHER EMINENT GENTLEME1T.

Complete in two imperial octavo volumes, of more than fourteen hundred pages of

double column letter press: and upwards of three hundred

elegant illustrations.

THE CYCLOPAEDIA OF ENGLISH LITERATURE, now presented to the
American public, originated in a desire to supply the great body of the peo-
ple with a fund of reading derived from the productions of the most talented
and the most elegant writers in the English language. It is hoped hereby
to supplant, in a measure, the frivolous and corrupting productions with
which the community is flooded, and to substitute for them the pith and
marrow of substantial English literature ; — something that shall prove food
for the intellect, shall cultivate the taste, and stimulate the moral sense.

The design has been admirably executed, by the selection and concentra-
tion of the most exquhite productions of English intellect, from the earliest
Anglo-Saxon writers down to those of the present day. The series of
authors commences w^th Langland and Chaucer, and is continuous down
to our time. We have specimens of their best writings, headed in the sev-
eral departments by Chaucer, Shakspeare, Milton, — by More, Bacon,
Locke, — bv Hooker, Taylor, Barrow, — by Addison, Johnson, Goldsmith, —
by Hume, Robertson, Gibbon, — set in a biographical and critical history
oi the literature itself. The wJwle is embelUsked with splendid wood en-
gravings of the heads of the principal authors, and of interesting events con-
nected with their history and writings. No one can give a glance at the
work without being struck with its beauty and cheapness. The editor,
Robert Chambers, is distinguished as the author of many valuable works,
and as joint editor of Chambers's Edinburgh Journal.

To those whose educational privileges are few, who reside at a distance
from libraries, and whose means are limited, such a book must be of un-
speakable value, — A WHOLE ENGLISH LIBRARY FUSED DOWN INTO ONE
CHEAP BOOK ! Any man, whatever his avocation or his location, may thus
possess, in a portable and available form, the best intellectual treasures the
language affords. To those more fortunate individuals who may have the
advantages of a regular course of education, this multum in parvo will be
a valuable introduction to the great galaxy of English writers.

As an evidence of the great popularity of the work in England, it may be
stated that no less than forty thousand copies have been sold in less than
three, years ; and this almost without advertising or being indebted to any
notice in the literary Reviews.

In addition to the great number of pictorial illustrations given in the
English edition, the American publishers have greatly enriched the work by
the addition of fine steel and mezzotint engravings of the heads of Shak-
speare, Addison, Byron, a full length portrait of Dr. Johnson, and a beauti-
ful scenic representation of Oliver Goldsmith and Dr. Johnson.

[£p~ Booksellers and Agents supplied on the most liberal terms.

GOULD, KENDALL & LINCOLN, PUBLISHERS, BOSTON.